Considering they told him he was no longer part of their plans for any forms when the club is going through a crisis(due to Tom Maynard's death) and are now lacking batsmen it shows that this was more than just a lack of form, age had caught up and he is sadly no longer good enough to play at county level.
I was born too late to see him play Test matches however he clearly had ability as shown by his 100 hundreds in First Class cricket so I'm guessing it was his temperament that let him down. Will be a shame to see him go and will also be interesting as a Surrey fan to see what they do for FC matches without Ramprakash, Maynard and possibly Hamilton-Brown(depending on when he feels ready to return to Cricket).