Hmm, you bring up an interesting point. I'm just not sure how valid it is. Complaining about massive new ride additions can take you down interesting paths. I think history will serve us well here.
E-Tickets of
Disneyland Resort (this is as best as I can remember so be sure to remind me if I miss one)
1959-Matterhorn, The New Autopia, Disneyland Monorail System, and Submarines. Time since last E-ticket opening (TSLEO)=N/A
1967-Pirates of the Caribbean TSLEO=8
1969-Haunted Mansion TSLEO=2
1977-Space Mountain TSLEO =8
1979-Big Thunder Mountain TSLEO=2
1987- Star Tours (debatable) TSLEO= 8
1989-Splash Mountain=2
1995- Indiana Jones=6
2001- Grizzly River Run, California Screamin, Soarin TSLEO=6
2004- Tower of Terror TSLEO=3
2008- Toy Story Midway Mania= 4
2012= RSRs TSLEO=4
You notice something? How the years between E-Tickets is getting progressively smaller? Disney Parks aren't stagnating. It's true that Eisner ushered in a pretty bad culture that exists to this day. However as far as building new things current management has done a pretty great job.
Notes: I think it's worth mentioning things like Tiki Room, Jungle Cruise, etc. I'm not sure that they're E-Tickets but still all the same pretty noteworthy. Walt was prolific. However reading a book about Disney history can be slightly confusing because they're condensing decades of history into a couple paragraphs.