I probably have a slightly different POV from most of the folks on the board since I work for a travel agency that is dedicated to Disney Travel, I have found especially during holidays and busy times of the year that there are defiantly not enough rooms sometimes, I've seen it on almost ever class of hotel on property value, moderates, and Deluxe hotels do book solid for a variety of reasons.
In the slower seasons Disney shuts down parts of hotels for refurbishment, during really slow times like right after 9/11 they shut down entire resorts and unfortunately stopped work on the second half of the Pop century. More recently, they have been doing a lot of work on the various resorts this past winter and spring much of it sorely needed. When I asked my contacts at Disney about what the plan would be if attendance hit those levels (or worse) again, back in January the response was they would use the down time to refurbish those resorts that needed it the most.
Internet, this topic comes up all the time, at WDW you're going to pay for it unless you go off site, but at least you can pay for it now, a few years back it wasn't there at all! They had dial up in most rooms and you paid way too much for the privilige. Most 3G wireless cards seem to work well on property which is the route I've gone for the past 3-4 years, with all the travel I do it saves me a lot of money on those 10-12$ night internet fees. ..
I do think that Barbara has an excellent point, it's hard for larger families to get affordable rooms on property. If you have more than 4 people in your family you are pushed into higher priced lodging, the family suites at the Music are really great and I have had client's rave over them but they cost the same as 2 rooms at the same resort, so no real cost savings but you do get the kitchenette and two bathrooms! There's only one moderate that will sleep 5 and that's the Alligator Bayou buildings in Port Orleans, and the trundle bed is very small, if the 5th person is not under 5ft don't even try it! The Cabins at FT Wilderness are nice but not for everyone, and they are priced between the Moderate and Deluxe Price Points. The Deluxe resorts do sleep more thanks to the pull out twin sleeper sofa in most of the rooms (and yes they are actually comfortable as well surprisingly enough) but now your getting up there, and of the two cheapest deluxe resorts; Wilderness Lodge and Animal Kingdom Lodge, only the Ak lodge has them since the WL rooms are decidely smaller. The DVC offerings including the new Treehouses can be cheaper but you either have to have a very large family, or travel with other families and split the cost, not an option everyone can take advantage of. Part of the reason for the disparity is Florida has very strict rules on hotel room occupancy based on the square footage of the room, they had to get special disponsation to add the trundel beds to POR. This leaves Disney with 2 options - new construction or create suites like they did at the All Stars Music resort by knocking down a wall between two rooms.
I guess in Short too many rooms? No not at all, Too few rooms for larger families? Yes at the value resort price levels, there are plenty at the DVC/Deluxe resorts price point with the new construction but that will change in the future as more people buy into the DVC.