Sorry in advance. This will be on and off topic...
First, one of the reasons that I'd bet most of us brew is that we hate the taste of commercial brew. I've never had a Fat Tire Ale that was an original so I have no opinion. It might be good - it might be bad.
Second, we are people. Therefore we are full of opinions. The internet, and forums more specifically, almost beg us to let those opinions be known. Being judgemental of people's opinions when a topic that they feel strongly about is just as bad as those people being judgemental about the the topic they are responding to.
I made a Fat Tire Clone as my first homebrew from a recipe I found in "Beer Captured" by Tess and Mark Szamatulski. I did the mini-mash version. I am neither a fan not a hater of this brew. I will tell you this - It's a brew that I feel requires patience. This could easily be the OP's problem. I know mine was flagging down a troop of monkeys for the first month I drank it. Now, the banana aroma is completely gone. It tastes "OK" but is not something I see myself brewing again. I have 2 bottles left that I will probably let age another 3 or 4 months just to see if it tastes that much better...we'll see. My point here is that maybe he should wait awhile.
For any interested, here's the recipe I used:
1.5 lbs Belgian 2-row
8 oz US 80L Crystal
6 oz German Munich
4 oz US Victory
3 oz Belgian Biscuit
30 minutes steeping and then ladle sparging
4 lbs alexanders Pale Malt Extract Syrup
2.5 muntons extra light dry malt extract
1/3 oz yakima magnum @15 AA
start of boil
1/2 german hallertau Hersbrucker
1 tsp of irish moss
45 min into boil
1/4 oz willamette
50 min into boil
yeast: the recipe calls for wyeast 1762 belgian abbey II. I used White labs Belgian ale WLP550
