I have a dualist approach to genres and music.
The way I see it, genres are only there to help describe the general aspects of the sound of a band, mostly for the benefit of those who do not know what the band sounds like. It's easier to say "well, Kalmah is essentially Gothenberg metal influenced by thrash with harsh vocals." then "Kalmah sounds like vocals from band x, guitar that's fast, like band y, with riffs and leads sounding like bands z and w."
I use genres because I believe that you can classify many aspects of a band's sound, making it easier to communicate the abstract aspects, such as how the riffs are written, how the vocals sound, how the guitar sounds, how the leads sound, how the drumming is, etc. etc. etc.than manually describing each of them. It also tends to give people a better mental idea of how they sound than manually describing it.
I also see genres as mutable, and able to modify eachother. Like saying band X combines Brutal Death Metal with Power Metal type leads, and a combination of both Power Metal and Brutal Death Metal vocals. If they are predominantly Brutal Death Metal that incorporates parts of Power Metal, then they would be classified as Brutal Death Metal influenced by Power metal, etc.
Take the example of Electrogrind. Electrogrind is a new type of Grindcore that was created by taking Grindcore music and adding in some electronic music sections and such into the mix. It is much closer to Grindcore, so it would never be accepted as being considered a purely electronic genre, it's a fusion genre that originated with Grindcore and expanded the Grindcore sound to include electronic sounds as well. (listen to anything by Genghis Tron for an example of Electrogrind.)
But the second aspect of my view on genres is this: I don't want anyone let genres get in the way of listening to music. I'm guilty of it at times. But I try not to.
I will listen to pretty much anything once, to see if I enjoy it. Example: I always go on huge rants about how pop music blows enormous chunks. However, I like quite a bit of music by Lily Allen, Christina Agulera, Feist (although she's kinda indie pop) and a couple others. The part that makes me hate so much pop is the fact that for the most part, the music is designed not with music itself in mind, but with how well it will sell in mind. That paradigm generally leads to music that is not good sounding to me, and sounds too plain, and overproduced. I prefer bands/artists who write their music for the creative reasons, and not simply money. They don't care if it sells well or not, and they're just doing it for their own reasons. Black Metal is an extreme example of that: They go out of their way to make their music sound like ass, to be obscure, and to do whatever they fuck they want (burning churches and such). Sure, I still hate some Black Metal, but at least I can respect them for writing music for themselves.
I'd go into an even longer rant, but I'm fucking dead tired. disregard any typos or shit in here. I just worked 8 hours and I've only had 1 hour sleep or between now and 11 PM 2 nights ago, so I fucking need to sleep.