I think knightfan7 is right in that the recruiting game has completely changed because the technology has, but I don't think that the answer is to restrict the kids more, which is what an early signing period would in effect amount to. The coaches are all for an early signing period because it takes someone they sell off the market early. It would also give teams more leverage to pressure kids to sign early on threat of their offer being pulled for an early signer.
Also, the number of decommits tends to rise and fall relative to a program's strength and coaching stability. A program that is in turmoil, has a bad record over a few years, or whose head coach has a good chance of being let go in the next year or two will see far more decommits than a stable winning program. Even after going 4-8 in the wake of EL's injury, Schiano didn't have a bunch of decommits, because he had the credibility of his program-building record to stand on. We'd been to five bowls in a row and there was a lot of excitement around the program that has been missing since.
Us going through this is a transitionary event. Calling for sweeping changes that Saban, Harbaugh, Meyer and Miles want may be throwing out the baby with the bath water. I know why they want it; it will benefit them. Will it benefit us, though? More importantly, will it benefit the kids who have to make these life-defining decisions? I'm not sold on that, and until I see something that does change my mind, I will urge extreme caution.