This will now sound contradictory, but I think that the FA's reaction is over the top.
To me 'punishment' is meant as an example to others not to commit the same act.
So although I found Suarez's biting bit appalling in a 'human being sense' , in a footballing sense I think it was less of an offence than say jumping in with two feet and studs showing.
I know Suarez has done this before, but we've all know of players who have a reputation for dodgy challenges, elbows, raking Achilles with studs etc - and also repeat the offence.
So although to me, I think Pool should have sacked him, as presumably he must have had a written after Evra (and biting just wouldn't be accepted anywhere outside of sport it seems - rugby and boxing come to mind), I don't think that the action, in a dangerous play way was worse than a bad challenge. And, although Daffy did bite someone, I don't see that the FA need to really worry about it catching on and so issue a long ban as a deterrent.
As a thought, maybe the FA should start a points system. Each yellow card should be assessed for type, and each time a player gets a card for a similar type of offence, that points tally increases. Once a tally reaches a certain level, an auto red is issued. Repeated reds for the same offence extends the ban period. Mind you, then Bale would have got an auto red for repeated diving...so maybe not a good idea.