I can understand your point of view - I too would love to see a couple of new attractions.
However: new hotels don't necessarly mean that the resort reaches its capacity.
Disneyland Park has a capacity of just under 70.000 guests (if you really want to squeaze them in, I think the park could even hold 80.000) per day. Currently, it reaches these levels just on a few days throughout the year (Halloween, Christmas Day, Easter Weekend, New Year's...) There are many under-developed seasons, in which one-day-guests are hard to get. Judging from the current occupancy rates of the hotels at the resort, one can see that they are going strong almost all year round. A few thousand beds more would not change that by much (actually, with all the new hotels opening, and the bad economy for tourims I was surprised to see that the Disney hotels only had a slide drop in their occupancy rates last year) - and they could use their capacities better during the off-season.
You should also not forget that the first of the new Disney hotels is supposed to be a business travel hotel right next to the new convention centre. I doubt that the clientele they're aiming at will affect park attendance much (except for after-hours special events).
And: the resort has actually lots of capacity, that's not being used. (Did any of you have to wait more than 30 minutes for Rock'n'Rollercoaster???) You could also "activate" a lot of capacity that's not used right now, like operating a second riverboat in Frontierland or having a second day-time parade (like they used to have in the 90's). And then there's Autopia, Les Pirouettes du Vieux Moulin, the Keel Boats...
Of course, a new attraction is wanted and maybe needed to attract people to the resort. But not to add capacity (well, at least not as primary reason), but to get people to visit the parks - and these shiny new hotels.
So I rejoice when I hear them planning new hotels (besides that they fill Euro Disney's coffins a lot better than any new ride could). Besides that this is actually changing the resort's infrastructure (which is a HUGE aspect), new rides and shows might be a small benefit of these added rooms on property...