Something I think we all have to come to terms with is the fact that Disney doesn't think of it as no new attraction coming to a specific park since such and such year. They really seem to think in terms of resorts overall - maybe all the new stuff has gone to only one park, but that park is still part of the resort so in their minds "it counts." We may not feel the same way but it's like the whole Disney Parks branding. They seem to be more comfortable with generic categorizing.
The company got too expansion-happy in a short period of time in the early 90s and instead of plussing what was already there a bunch of new parks opened up with not a whole lot to do in them. It takes a long time for big egos to admit mistakes.
California Adventure got some serious TLC, and many of the other parks are due for some as well. It's a question of how much money certain people are willing to spend and how they plan to stagger it all out.