I for one am glad Flame got nerfed, though I think it was nerfed a bit too hard (Went from 3000 to 500 (I think)? 1500-2000 might have been a better place to start, if I'm off, a 50% nerf to start and go back up from there). Once they have the proper score ratio down, I think they'll probably bump everything up a bit to make current leaderboard scores attainable.
The problem Blitz has is score creep effects star outputs. So, things like GS the setlist become easy for anyone to do, so they can't simply "buff till they get it right".
Ultimately, the issue is that, yes, people play for the leaderboards even if they don't all play to be #1 on them. Everyone likes moving up on them and beating their own score. But there's more to it than just that, and if it takes a nerf to balance things out a bit, then I'm all for it.
My other balancing thoughts:
Synch seems a bit too powerful, but I also find it annoying to use personally so I don't. You can GS songs using only synch though (not even hitting notes), which I think isn't a good thing.
Blitz Mode could use a bit of a buff, just to make holding combo a little more important.
The problem with Jackpot is that it tracks everything, so flames, blast, whatever gets a boost from Jackpot. For some reason, I don't think point doubler does this. Jackpot is actually hindered by the larger hit window though, as it makes changing tracks dangerous.
Shockwave feels week. I think it needs to go just a bit further / energy used (I haven't used it in a while though).
Runaway Note is useless. Easy to miss initially, and can hinder the use of other powerups. Maybe slow it down just a bit and make more appear, or make it worth a lot more. Does Jackpot/Doubler effect this score? If it does, beware of exploitation.