A lot of interesting replies, but all of them missing the point.
The question is, what would be better, the x1 rate or an x2 rate? Or even x3?
No one wants a x12 rate or some such. We all want to enjoy this huge world, and not just rush through it; otherwise we could just play the retail version.
But do we really want x1 rate? There were lots and lots of grindy stretches in the original Vanilla WoW. No one misses those. The game should be fun. You should be able to do all the fun quests and skip all the grinding bits.
The x2 rate would accomplish exactly that.
Yes, there are 5000 players around right now; but chances are that those numbers will be dwindling soon when people reach lvl 30 or 40 and find themselves in a stretch in which they dislike the dungeons and the areas and don't have any fun anymore.