The incentive is the same as the incentive for them to do anything: democratic process and popular pressure. If this is such a no-brainer it should have wide support among Colorado voters. This is much better than having unelected federal judges thousands of miles away declare the issue by fiat.
> The loophole enriches their constituent law enforcement organizations
A. It's not a "loophole", it's simply the lack of any explicit law directing refunds. B. I'm not familiar with Colorado state finances, but I seriously doubt that refunds from vacated convictions would have any significant budgetary impact at all.
> ...if the law as written is encouraging abusive behavior from law enforcement
Again, this isn't "abusive behavior". It's simply lack of a law authorizing what the petitioners demand. I wouldn't be surprised if it was simply that nobody thought to write and pass the law, given the relative rarity of vacated convictions.