I think it is a reflection of the times. For many years, the luxury of full-service dining (for either every meal or even just one meal per day) has been something only the rich and the foodie would pay for. Now, everyone has taken to the idea that the eating as a big part of the whole experience. We have folks with photo galleries dedicated to photos of the food -- that was considered kind of "strange" when I did it in 2000. (Gosh -- Is it time I reposted those photos, as a sort-of homage to nostalgic food porn?)
Two things work against building more restaurant capacity anytime soon. First, the American consumer is utterly unpredictable. Given the focus on low prices, it is only a matter of time before the bubble bursts, and people stop paying for table service meal-after-meal. Therefore, it isn't safe to expend a good bit of capital on building capacity that may only end up sitting empty as soon as it is built. Second, the lack of capacity and the consequent difficulty in getting ADRs itself may raise the value of the offering in the eyes of guests.