99.99% of any genre sucks. thats just the nature of the music industry.
more like 50%. 99% numebr is onyl for metal.

you either get metal or you dont, you obviously dont.
and i do listen to other genres you know. when im listening to country music (yes nuke likes _some_ country, it appeals to his inner redneck), some cash, hank I/II/III, some coe (the **** from the 70s with the profane as **** lyrics), any of the outlaw ****, are good, but i really dont care about most of it. the **** they play on the country station doesnt even register as country to me, most of it is either right wing propaganda or ****ty pop country. i love the country and metal tracks in starcraft 2, i always crank my speaks when those come up.

my theory about why so much crappy music is this:
most people are dumbasses. and as a result are hooked by simple concepts, like 3 chord songs, sexual themes (people are perverts and sex sells). anything shallow will sell big, because most people are shallow individuals. this creates a situatiuon where artists, who are not very good, and through shear marketing to the heard is enough to make them big. why do you think **** like classical and opera are so unpopular with the heard. the quality of the music is top notch, so why the **** dont you see cars full of teenagers blasting bach or wagner? because the industry rides the teen market and floods it with music with lyrical themes that are relevant to them, and they buy it up in droves.
and as far as games go, especially games where you have hulking spacecraft, big stompy mechs, warfare, blood, what have you. metal fits in all of them kinds of games, freespace included.
and this song (or at least an excerpt of it, its kind of long and drawn out in some places) is absolutely begging to be put in freespace:
http://www.youtube.com/watch?v=cS6HXQa9uMEgood one for a suicide mission into shivan space. play it with into the lions den. the song structure has a good parallel with that mission. the long lead in gets you past dive dive dive, and the intelligible lyrics play while you cross space to the first comm node. during the combat parts they lyrics are not in english (this song seems to have lyrics in several different languages). and the finale of the song coincides with the run like hell for the node portion of the mission. and this brings up a good point, find a good structured song, and design a mission around it. make the combat occur during the solo. i mean theres a lot you can do to make the gameplay fit in well with a particular song.