Ending Dragon Ball GT, was it disappointing?

Okay lets talk about the ending of Dragon Ball GT for a minutes. I found it saddening that Goku returns to watch this match and then disappears. It just didn't seem like Goku to me either. He's got this dumb *** grin the whole time, It's like it's not him. Why would he show up now as apposed to when people he knew might still be alive??