Actually we should consider ourselves lucky that Brady was so young when the Patriots went on their Super Bowl runs.
If the Patriots had gone on the same run with Bledsoe (big if ha ha), then Bledsoe would have probably been looking at retirement around the same time as Bruschi, Harrison, Vrabel, and Brown were all leaving the team. That would have left a nearly impossible leadership void to adequately fill all at once.
Brady has been the glue keeping the team together through a pretty challenging transition, and I'm completely OK with him entering a Moss-like phase where he knows when to work and knows when he can rest. He's earned it and the team won't suffer as a result.
Hopefully we're saying the same thing in 6-7 years when "grizzled vets" like Mayo and Merriweather are holding the fort down while a new rookie superstar QB comes up to speed.