You ask very good questions and hold incredible insight into what an answer might be. In my opinion, you've hit the nail on the head with the idea that more and more students are submitting applications for the same number of spots each year. It's difficult for universities to add additional seats (think in terms of housing, teaching loads, etc.) so with the exception of a little wiggle room, large increases aren't likely.
There are many theories on the phenomenon of applying to many schools and the ways to deal with it. It's an interesting discussion circulation in the enrollment management areas of higher education. Perhaps with your interest and insight you would consider a career in higher education?! ;-)
It's been very good to me, and I never had to leave college!
Best wishes to you in your collegiate search -