I like Bob!
Yeah, it annoyed me when sh*t went wrong because of his urge for the drink, but come on, that was incredibly realistic! People just assume that when the chips are down, they are going to be able to shape up and rid themselves of the habits or vices (or both) that kept them down for so long. Or, those habits or vices that kept them GOING for so long.
Without question, people who suffer from alcoholism or nicotine addiction, etc. can survive in a world like the one we see on TWD. But to assume that all survivors are the ones who never dealt with that temptation? Give me a break. Just because they are strong doesn't mean they aren't "weak".
Bob has shown a lot of growth and loyalty. I had my doubts when the beginning of the 4th season aired, and I went so far as to blame him for killing Karen and David. The loose cannons are always the first ones we accuse. But he has really come a long way in terms of character development and I really appreciated what we learned about him at the beginning of "Alone".
As much as I truly hate losing our original members, I enjoy it when TPTB give us character development or at least some insight on the newer characters that they introduce. That is not to say that I would welcome an original group member's death simply because we had become attached to someone new. But let us not forget that the Greene family was not part of our original group, and we have since grown to love Hershel, Maggie and Beth.
I also truly enjoy Tyreese. I don't know; there is just something about him that seems so desperate and "good". His vendetta against the person who killed Karen whilst never knowing if his sister was still alive truly annoyed me, but I think that may have been a flaw on the part of the writers. One of the few, I may add. But his agreement to kill Lizzie followed by his apparent forgiveness of Carol just solidified, for me, the kind of person that he is. He seems a little lost; perhaps still in denial.
Getting back to Bob, I think he has suffered a great deal, before and after the ZA. Does that give him an excuse to act reckless with the group simply because he wants a drink? Of course not. But he is also still a human being, struggling with his old (human) demons and probably hoping that he can pull off both. He isn't a monster; he is simply a human being, struggling with a past, pre-ZA weakness. Wouldn't it be great if we were all strong enough to do the same?