The way I understand it is in the distant past when VC paper was first created it shipped with two filters for spilt filtering. This caused problems with people used to graded paper and wanting graded VC paper. That led to the current filter sets.

Personally I find spilt filtering quick and painless. It's not extra work for me so I use it for everything. The only point I'll disagree with Rbarker is I find it quicker then single filter printing for me.