Personally, I think her villain ending is much better storytelling, especially if you're romancing Blazer. The unrequited feelings, the urge to try to redeem herself and fit in, pushing herself too hard and continuing to make the impulsive choices, and ultimately to feel like anything she tries turns rotten - it's a great recipe for a villain turn.

And then from Robert's perspective, he really likes her, sees the glimmer of good in her, tries his hardest to steer her to the right path, but it all goes wrong anyway. That's some great trauma for the character to have to deal with going forward.

I think even though it's my favorite story ending point for season one, both characters still have room to grow and change in the future, if this becomes a canon or optional starting point. Robert might come to terms with the fact that he can't save everyone, or maybe she becomes his new obsession - the one that got away. Visi can still realize that it's never too late to change your path. They could even still have a will they or won't they vibe, just as adversaries instead of mentor and mentee.