Why not nginx?

Why are most of the Turnkey web based appliances based on Apache rather than nginx? (wordpress, owncloud, etc.)

Any techical reasons or just old a habit?

Apache is a heavy beast and I'd think nginx would be a better fit in lightweight Turnkey appliances.

I would definately use Turnkey more often if all those appliances came with nginx rather than apache.

I apologize if this question has been asked and answared before, I did a quick search but wasn't able to find any related discussions.