The problem is simply how MC/mods handle lava in the first place. It's completely unrealistic to treat it as a liquid as you would for example water. If a mod attempts to be somewhat realistic they can't use anything that uses 'liquid' lava; lava even when fully heated is very viscous. Good luck pumping that any distance, not to mention that there are probably no pumps who could handle that heat.
I don't think "mushroom taco" was thinking about the realism when talking about lava as a heat source as imbalanced, but I could be wrong. I don't find realism to be too interesting in itself, but I wouldn't mind some changes to how we handle or use lava. Removing the use of buckets, pumps, pipes, etc, is fine, but it must be replaced with an equal amount of interesting mechanics.