I hesitated somewhat, but that's generally the case with almost anything you say on the internet.
Depends on what wrong means to you. If we're talking about creating a more effective character and this one particular feat at 25th+ level... then yes, that is what I'm saying, with the stated exception that it _may_ be possible to find fourteen other more effective feats. I haven't seen anyone provide such a list for any singular character, but it is possible.
If we're talking about making a fun character, then I hope I've made it clear that's not contingent on perfect math. Fwiw, I often purposefully play a less effective character than is possible, because I find it more enjoyable. And I certainly often find other feats to take before Expertise because they're important to my character concept, such as multiclass feats.
If you think that +3 to attack doesn't make a notable difference in a character's effectiveness, though, I will stand by my statement.
But, if you enjoy missing more often, then by all means don't take Expertise. Realize, of course, that your group may find it less enjoyable to have you missing more often, but they might not care. A lot of that may depend on whether you're a leader or not.
In the case of certain leader types, like tactical warlords and clerics with astral seal, missing may cause other party members to miss, detracting from their fun.
I understand, but there are an awfull lot of people that game to game, not to "win" the game. We also play Savage Worlds, and most of us have taken major hindrances - because it is fun to work around them.
IME, most people remember the memorable fights becuase they had a disadvantage they had to overcome. +3, to me, is not a real disadvantage that needs to be overcome, especially when we can change that 16 we need to hit to a 10 by using a power that attacks another defense.