Ok, time to wade into this murky waste land with some pruning sheers.
Firstly I'll place myself in the camp of 'I really couldn't give a **** about LA'. Not one of his fanboy's, not one of the people who hates him.
I think this comeback is partly due to his drive as a competitor, but mostly due to publicity. However whether he's in it for the attention he gets or the attention his charity gets is irrelevant, this comeback will no doubt increase donations to livestrong and the cancer causes it supports and I think that is, in the end a good thing.
Oh and I'll think it'll be hilarious when he doesn't win the TdF because all the fanboys will have to go and eat huge quantities of humble pie. Same to the haters when he passes ever drug test (for whatever reason...).
I don't think he'll make the racing more interesting though. As an older athlete he won't be able to attack like he used too so he'll have to win his races in the time trials, riding steady to limit his losses in the mountains which equates to boring racing.