Just calling it a "miss chance" instead of concealment doesn't really make much of a difference. I mean sure, if you explicitly say it doesn't affect precision damage, then fine, but the intent of the rules behind precision damage is quite clear:
If you're dazzled, a condition specifically affectiong sight, and you're getting a miss chance because of it, then it makes sense that you wouldn't be able see well enough to sneak attack. And again, dazzled is just one of those conditions that's really easy to apply, often not having a save to resist and it's balanced around that, so this isn't a minor upgrade, it's a huge upgrade.The rogue must be able to see the target well enough to pick out a vital spot and must be able to reach such a spot.