Well, if we go into the way-back machine, ten years ago, we also had four carriers, at least here in Houston. Let's see... Houston Cellular -> Cingular -> AT&T, Aerial Communications -> T-Mobile, SBC -> Verizon, and I guess Sprint -> Sprint.
(Well, we also used to have Nextel, which was absorbed by Sprint. Does that still exist, or can I legitimately claim that we've lost a carrier over the past ten years?)
Actually, ten years ago, what I remember was that there was a lot more wheeling and dealing on rate plans. At one point, for example, I had a T-Mobile plan for which all of the U.S. and Canada were my home area. Now, it seems there are assorted deals and discounts on the phones, but the diversity of rate plans just isn't there.
I don't have my ancient phone bills around, but in real (inflation-adjusted) dollars, I'm pretty sure I'm paying about the same now and I used to pay, but now I've got effectively infinite talking minutes and effectively infinite web bandwidth, which of course didn't exist back in the day.