I'm not sure what games you're watching, but Ime hasn't shown me anything to indicate that he'd be ready to contribute offensively or defensively in the near future, let alone be a starter or primary role player.
If Ime played solid D and understood the system, I'd say you had a good point....but he doesn't yet.
If Ime hit shots with regularity when left open, I'd say you had a good point...but he hasn't yet.
I'm not saying this guy will never come around, because I think he has the potential to be a regular contributor. In fact, if there was ever a guy that I think would blossom as a second-year player, it'd be this guy.
I just don't think he's worth much of anything to the Spurs right now...