I really give no fucks about rank and don't care about arbitrary numbers in front of my name. I know how good I am personally and that's all that really matters. But with points, the reason hards give so much more, is that it is a lot easier to SS them with mods. The more mods you use, the more points you get. The higher your acc is, the more points you get. AND, on top of that, if you SS a map you get a points bonus (this was stated by peppy himself and I may or may not have been the cause of this). Hard maps are also way more likely to have the most plays on them, thus deeming them to be "competitive maps", which give more PP reward. Mathematically and statistically speaking, the more plays the map has, the more competition there is. That is just the numbers speaking for themselves. Does that translate into a more interactive and skill-based environment? Probably not. Yes there is a formula to lessen the weight of play count on easier difficulties (for example, think like multiplier times .2[easy], .4[normal] .6[4star], .8[hard5star]), but that can only help so much. The reason the hards have more plays is that there are naturally more players who can play those difficulties than the insane ones. All of these factors lead to hard maps being worth a lot of performance points. Should you care? Probably not.
I don't think it's overly impressive for someone to farm hd/dt SS on 475 note hards, but to each their own. You should be focusing on making yourself better and not worrying about how many points you get for completing a map. If I went and played a bunch of hard maps and went up 200 ranks today (I can do this, it's not hard), I would not think to myself "hey I have more points now, I got better today". I didn't get any better at all. I didn't improve anything. Just my number in front of my name. Who the fuck cares? You get nothing for having the highest rank. No money. No rewards. No prizes. No free supporter. You don't get anything. If you hate someone's score so much, go beat it. Stop bitching about it on the forums. If you think you are so good and deserving of a higher rank because "oh look at me I can play insane maps and do harder things, but this person booboobooboboo", then go do exactly what they did but better. Go try and play for a number instead of for enjoyment like they do. You have to decide yourself why you play and not for the reasons others play. If you want your number to be bigger, go make it bigger. I'll keep playing my maps that I personally find fun as shit to play and I will keep playing them and working towards my own goals. Who cares about the stupid fucking number. If you wan't to get better, go get better. Don't worry about what other people think. You will start to hate the game for what it is the minute you stop playing it the way YOU want to play it and for the reasons YOU play it.