Frankly, I don't care about the posers. Just push them aside on your way to the moshpit.
Meanwhile, it will bring in more real fans, which is always good.
But the best part is of course, more money for the bands. Which allows them to improve the production (not necessarily make it cleaner), spend more time in the studio, afford better instruments and amps, hire better producers, and bring in more and better extra musicians for shit like string sections. Listen to Rhapsody's Symphony of Enchanted Lands (all midi) and Symphony of Enchanted Lands Part 2 (when they had money), which is done with a full orchestra. Way, way better. Imagine what they could do with a kickass budget.
The downside would be that there might be more pressure on a band to release stuff, and to produce singles and stuff. But any band worth listening to wouldn't cave to that.