I love the first two games, and played them years before Curse came out. And I never had a problem with Curse, when it came out I loved it too. I don't remember going 'wah, this does not respect Ron Gilbert's vision!', but that's probably because I was busy enjoying the game. Yes, it's different from the first two but it was also similar to other Lucasarts adventures of the time, like Day of the Tentacle and Sam & Max Hit the Road, (toony graphics, voice acting) so I didn't find the different art styles and controls too jarring. So in short, in my opinion Curse did not destroy Monkey Island.
And to be fair on Escape, I replayed it recently after finally getting it to work on my laptop, and it's actually better than I remember, rating higher than all of the King's Quest games except for KQVI. But maybe that's due in part to Tales convincing me that yes, adventure games really do work in 3D. Maybe now I'll finally pick up the Sam & Max episodes...
"Gentlemen! Please! You can fight like itsy bitsy babies later. Right now we have adult name-calling and mud-slinging to attend to."
- Dr. Nightmare, Attorney at Law