I mean the basic framework for each of these games are on point. The game design is really at Blizzard, they know which tools to give and more importantly (and this is where a lot gaming companies go wrong imo) they know what not to give and what the players expect.

Larian studios released BG3 a few weeks ago for example, but the game has the same engine as Divine Divinity, something that veteran players don't expect, nor where asking for. The game is great, but from a game design point of view it's something that isn't enjoyable (for veteran players at least)

This is something that Blizzard understands, it's just the next step at Blizzard nowadays seems to be: "how can we profit from that". And this is where they seem to search the fine line between game design and milking the cow.

Now here's the really shitty part, they can afford to fuck up because they have such an amount of resources to their proposal.

In all your examples the basic framework is really strong:

• Starcraft 1 is probably the first game that knew a professional competitive environment and Starcraft 2 basic franmework has all of that, I think Starcraft 2 is probably the least worst of your examples, but it feels like the micro transactions are taking away a lot of focus that could be put to other things
• World of Warcraft Vanilla was one the most challenging MMORPGS of their time (though we can't deny the game was also more toxic than) But the game has been through endless cycles of reinventing themselves, just so they would see a surge in game subscriptions. "TBC and WOTLK where amazing, so maybe this expansion is good again? right?" oh and ingame shop now...
• Diablo 3 is the most interesting one as I feel like it was the only game that was not true to it's core game design, and while the current state of the game is closer to what players expect from Diablo (the game is not that bad now) the very very very bad balancing in the first patches (I remember playing for 3 hours straight and actually have less than when I started, simply by dying and having to repair my gear)
• Warcraft 3 (TFT) was an amazing game. So they decided to remake it, no problem there and than release it while not finished... From what I understand the team that made the game warned that the game wasn't close to finished but the shareholders pressured the company to release the game too early, resulting in having the game claiming the title for Meta Critics worst rated game EVER

And since they have so many resources, if they fuck up too hard they just release a new game in the series and act like nothing ever happened.

They started working on Diablo 4 after they saw Reaper of Souls didn't bring the players back as they hoped. While there where plans for new expansions they board chose to just start working on a new game and not pay too much attention to Diablo 3 anymore. Pretty sure Starcraft is next in line. And if they ever want to release a new Warcraft RTS, just call it Warcraft 4 and they are good. That is the luxury they have with their resources and it's disgusting to some extend.

Anyway Game design wise the core is always great and a lot of resources go to that when they create a new game which is why they prefer to not publish a game if they feel the core design isn't that good. I sadly have never been able to visit Blizzard's Campus so I don't really have an idea how it is behind the curtains. I've visited Riot Games' campus in Los Angeles and was truly impressed what I saw there and from what I heard from some employees Blizzard isn't less. The people there "know there shit"

Anyway, I read a few books about game design but I am no way an expert on the matter, but if you're interested in the topic I can recommend this clip