The thing with cell phone plans that really bugs me is the fact that they are inflated to cover the costs of subsidizing the phones. I think selling the phones separately could lead to lower monthly costs since you're not paying for your plan AND the rest of the phone. Unfortunately consumers won't see any significant decrease with just one phone unless a lot of people buy it.
I figure a SmartPhone that is sold subsidized at $199 with a two year contract works out to about 10-15% of your monthly bill but it depends on the actual cost the carrier pays for the phone and the monthly package costs. So it would translate into a modest savings if the carriers actually discounted the packages on non-subsidized phones. They do not. So you're paying that extra 10-15% either way. Doesn't seem fair to me.
The added competition of customers not being locked into contracts is defeated by competing standards. Many GSM phones won't work on T-Mobile's 3G network and most of the handsets engineered specifically for T-Mobile don't work on AT&T's 3G. An unlocked CDMA phone would fair better since you would have legitimate choice between Sprint & Verizon. What we really need is an unlocked GSM/CDMA hybrid and we might see some real competition.
