That was one of it's problems, IMO. Android 17 in Z redeemed himself, and helped contribute to Goku's final attack at the end of Z.
Then he comes back in GT as an immense jackass.
The one thing I'll give GT is the 4th Super Saiyan level did address something I always found puzzling, that being why the ape Saiyan concept was completely ignored in ever super saiyan form.
Also, the Shadow Dragons had very good designs. But I tend to like pretty much everything Toriyama draws.
But still, hated the Android 17 twist.