Just watched the CMA thing for the first time. I don't quite get what's supposed to be wrong with it. Glenn looked intense as ever, Don was stony-faced as ever (and I say this with affection), Timothy had his usual, serious "I'm doing my thing as well as I can" look (again, said with affection) and Joe had his usual "I'm cool no matter what" thing going. I've never been a fan of this song, but this performance didn't bother me.
As for smiles, it would look weird to me if they were singing a lyric like this and smiling at the same time. Would look like they were just "the Eagles singing a song, because that's what the Eagles do well". They did smile at the end. Glenn's smile looked genuine to me.