Not like rooting really does THAT much on the network side of the spectrum, we arent adding 4G to our non 4G phones...
But yes, when I originally got in on the Android train, I purchased a G1 for full price, not the with contract price because I only had been with tmo a couple months... I had put @home and numerous other apps on it to alter the look of my G1, and basically rooting it, and running it with a custom firmware I view as no different than taking my laptop, destroying windows and putting Ubuntu on it...
Also considering Android is open source, means that modification is possible, and welcomed
ONE MORE POINT: Altering my device could be something as simple as buying a non-OEM Extended Battery, or as was done with a lot of phones as of old, such as the old nextels, case-swapping. We have more potential to ruin our phones and need to buy new ones from the carrier/manufacturer if we allow more people to root them (well at least the uninformed ones are REALLY good at bricking them)