Performance shouldn't be upped with HD when you can't play it anyway, so let the HD players have a reasonable bonus for doing well, not badly. It's just a different way of reading, as opposed to approach circles.
Many players argue that HD is just as easy as nomod once you learn to play it (trap notes aside). So how do you rate skill? The bonus was given to aim, but I still don't know if that's the right place. It seems like a patch-solution.
There is also the problem that some people play a map nomod and move on, setting hundreds of nomod ranks. But you also get people who use HD all the time and do the same. This is almost as bad as Hards vs Insanes, where different people play HD, compared to those who play nomod, and is almost impossible to compare the two other than to say the non-HD players have less skill because they can't play a mod, but by how much? Surely once they learn to play HD, they will be just as good if not better, but they're not interested.
I'm one of these people who never really delved into HD because it's not the challenge I'm looking for. When I mess up, it's not like my rhythm was bad, or my aim was bad, it's because I didn't fucking see the circle there, or saw it a bit late, putting my timing off, and that just annoys me so I don't play it much. I know I can get better at it, but why bother. I'm fine with a few less ranks, but if I learned to play HD really well, what then? I gained no mechanical skills by doing so, I just learned to read it, like AR10 doesn't give any bonus compared to AR9/8, because it's subjective. You just need to learn to read it. It is hard to rate something by it's obfuscation, which is HD and FL (memorisation).