Frankly, I don't know enough about melee mechanics to say if it forces them into suboptimal situations, but no one seems to have an issue with it.

I mean, they're going to be moving to hit the heart anyway won't they? Unless you mean some groups just leave their melee on the boss full time and let the ranged DPS kill the heart by themselves. I guess you could do that too - but in my group all the DPSers are on the heart anyway, so I'm just leaving myself out of the first one.