You know, if you want to search where Blizzard really turned towards different directions concreticly - it was somewhere AFTER WoW intial release. It is the point where everything become too over-cartoonish, they started to ressurect villians and characters, too much alter game world much beyond "in-game limitations" and hell lot of other things. Draenei from fucking alien monsters become "cute half protoss half demons and some anime", Outland from compleatly destroyed and absoluetly dead land of nothing floating rocks in space become "just another continent that in places looks like china mixed with cartoonish version of morrowind", Illidan who we seen clearly was dead in Frozen Throne ending is not dead and now again in outland for some reason, some long lost characters from Beyond the Dark Portal and overall it was just rollecoaster of some random shit just to please MMO players, not actual warcraft fans.
To mark point where they stop making RTS games and started making more RPG stuff is also very hard, because yeah, already, two points - plot and gameplay wise, also campain and scirmish is also different thing. Warcraft I had some character elements and limited no-base maps, Warcraft II had characters and heroes as special units that core of some scenarios, Warcraft II Beyond Dark Portal tells much more personal stories, Starcraft abadoned idea of Player as actual character like it was in CnC games and Warcraft 1-2, intermissions now not briefings but disscutions between characters, almost all campain maps have unique characters who need to survive or do some task. And Warcraft 3 in the end after total hell in development and almost complete abadoning of many ideas become RTS too, only major thing they added in concept gameplay-wise - Heroes now can go level up and pick some objects on map. If you for example turn off heroes and will play skirmish in WC3 - it will be absoluetly same strategy with same basic concepts, just probably less balanced than starcraft and missed some cool features you expected from sequel, because RTS part of this game was done very late in development, after abadoning their RPG idea they rushed RTS part in only like of year of development, and even thought 2001 they abadoned hell lot of ideas even from RTS concept.
Mission in campain - even more of them are hero centric or need to do you some specific non-RTS tasks and your army s just support for it. Reason for it because they slaped campain together from remants of all 10 different abadoned pre-alpha builds, because at time of 2002 blizzard started to get reputation of people who don't finish any games and don't keep promesies - Anounsed adventure games cancelled after all that hype and marketing, Warcraft 3 in development for like 4 years and every year they show different concepts but never proper playable game. People get tired of it and they needed rlise SOMETHING. So we get Warcraft 3 - some RPG, some RTS. Non best RTS, non best RPG, but still not bad game, actually great game that I count as objectively good. And even I'am more Westwood-dude, I think warcraft 3 did better job than CnC Generals - CnC Generals had hell lot of potential, ideas and ambition at RTS mechanics, but because EA - non finished, imbalanced and too rushed game sadly made Westwood lost this race for blizzard - I think they never at RTS balance toped Starcraft I, because Westwood tried to increase scale, add much more actual RTS mechanics and never managed to balance their game and polish them to make ideal competition games, and ironically focused on plots and campaings - but same time remained pure RTS at gameplay. At campains - sorry, starcraft. Warcraft 3 campain plots and cinematics awesome, Warcraft II briefings I like - but nothing will top awesome cinematics with real actors before and after mission.
Plowise - Warcraft 3 not very far from Starcraft, really. You have Arthas, he is like Kerrigan but even more bad ass, like he from start kind of wierd dude who become impotant because he is son of king of biggest human and after WarcraftI-II overall biggest kingdom in da world so he turned nuts, lost his soul and become not just "ha ha evil" but actually cold souless abomination of hate and killer and never become "good" again. He also killed Father and then Uther who carried urn with dust of his father just to put Kel'Thuzad there, and Uther also was not that good of a man, since he is blind religion beliver who can not properly teach and interact with people by reasons and become main paladin only because other duded died or lost during 2nd war.
Thrall story is kind of rayner story - it is just confusing becuause game about him was cancelled, nobody explain that he just dude who have some remnats of clans that did uprising in Alliance getto diet camps and he just trying to find new home, this is all. Athas not become good again, most of core human kingdoms destroyed, Uther dead, Orks now very small nation of survivers who live in some shithole in nowhere, Illidan dead (before retcons), Admiral Proudmoore dead, Draenor now some empty dead rocks with some demonic mutants. I don't felt there was some plot armor, nobody was ressurected from prvious game and nothing was just for sake of fan service exept some easter eggs.
And Even world of warcraft - vanilla wow released version have some problems of being MMO and world presentation, but it nit tried to be SUPER ULTRA EPIC MEGA WAR WITH ULTRA-DEATH HYPERPACE OVERLORDS. You just have actual world of warcraft - you can walk around in familiar and new locations, all bosses is actually not real world thread that much and not that absolute major dudes or characters - some lord of elementales, old god dude, Kel'Thuzad that was by plot remained in Lordaeron ruins in end of Frozen Throne, Deathwing's gf etc. and absolute major parts of vanilla - you just walking hours in some locations killing boars, sometimes find familiar places. It was what game promised - world of warcraft. I'd not wonder if they not expected WoW become so big - so they not maded that major events to left room for possible warcraft 4.
Warcraft 3 and WoW was not something planned - it was accidental games that result of messing with 9000 ideas same time. And only after their release old people started slowely left blizzard. After WotLK and Activison - if finnaly become this BAD comapany you tried to describe in your post. Only thing new team start to do - trying to repeat sucsess of War3 and WoW, transitional accidental games and start making games as fan-service for maximum big audience.
So after WotLK it become repating over and over but same time turned towards china and korea markets complatly. Every new addon old characters ressurected, time travel, world destroyed - this is just a bunch of STUFF. It's like terrible anime that on-goning for 900000 episodes. And for Starcraft 2 - they did absoluetly same. They don't know how to do other things rather than what are they doing now. 99.9% this is people who not was back when SC1 was made. It even not people who did WC3 and WoW vanilla. This is just division of Activision company that produce cartoonish hipster games by same cliches over and over, full of bad digital art artist. My joke about bydlo, woman and koreans (together with hipsters, teenagers, manchild femenists) - is their main target audience now. And this is their main work as part of Activision coporation.
If you want we can more talk about warcraft 3 alpha and beta versions and other cancelled blizzard games to help you view this game different than what it is.