Of course, this will all be subverted when the sequel comes out, but I can at least enjoy it for now.
I've come to accept the Marvel movies on the basis that they're a giant subsidy program for the industry at large. Talented actors and directors can phone it in and make huge salaries, which enables them to choose an interesting, low budget project next. I'd still rather those low budget movies got even a tenth of the budget that the average Marvel movie does, but oh well.
Like you said, the sequel to Infinity War will probably undo this and be disappointing in comparison, but I'm enjoying what we got.
The movies improve on the original in that regard, where Thanos gets the Infinity Gauntlet and murders half the universe just to impress a woman.
Also Chris Hemsworth's comic timing is great, he was a real highlight in Ghostbusters too. It reminds me of Ryan Gosling in the Nice Guys, a rare surprise that an actor can do comedy too that you weren't expecting.
As for Marvel baddies, yes, I generally agree with you. Their best baddies have been in the TV shows, namely Wilson Fisk's Kingpin and David Tennant's Kilgrave.
Also, considering what happened in the Infinity War arc in the comics, I don't think they could have done otherwise.
Fundamentally if all major conflicts don't revolve around it they are either completely out of its reach or being stupid.