As said in other threads by another brilliant poster:
I already did the math, and even if 25% of all eligible Blood Elf characters at max level were faction changed to High Elves, the end result would actually be a reduction of faction imbalance, not an increase. To be fair, it'd shift the numbers in favor of the Alliance, but instead of a 3.8% gap in favor of the Horde, it'd be a 3.3% gap in favor of the Alliance, for a 0.5% reduction in faction imbalance.
And that's only assuming that the absurd number of 25% were to actually happen when in reality the number of eligible Blood Elves which would be faction changed to High Elves is likely far smaller than that. At the end of the day, approximately 30% of eligible Blood Elves would have to faction change in order to have a detrimental effect on population numbers (Well, at least in terms of hard numbers. As Ion himself has already said, that's no longer a concern as far as Blizzard is concerned, so it's pointless to talk about that).
The funny thing about that argument, though? Is that they're effectively convincing Blizzard that they should do it. After all, every single faction change is $30 for Blizzard. If 25% of eligible Blood Elves were to actually faction change to High Elves? That'd result in a $7,401,780 profit for Blizzard. And all to reduce the degree of imbalance between the numbers of the factions? Sounds like a Win-Win for Blizzard, to me.
So its a win-win for Blizzard and reduces faction imbalance.