What the hell, I've never seen that chipstep sub-genre before. Must be recent. What is chipstep anyway...?
And um, while I agree it's pretty silly that there are very obscure genres like ska and apparently now chipstep too, and then there aren't more popular genres like hardstyle and orchestral, remember that the more genres that are added, the more complicated the whole system will end up being.
To be honest I think everyone should stop fussing over genres, really. Good music is good music, and if you've got the "generic" genres like techno, classical, hip-hop, rock/metal, etc... then there really isn't much of a need of getting into such detail. The only genre from the ones you mentioned that I've heard of before is hardstyle, frankly, and even that, I believe, does not warrant its own genre, especially since we have tagging now so we can just make hardstyle one of the tags.
Don't forget that genres change with the times, and new genres pop up every once in a while, whereas old genres may die down in popularity. If the staff added all these genres that are currently prominent, then with time the genre list really piles up, and we end up with lots of unpopular genres.
Oh and experimental can be put under miscellaneous.