I think the better question here is, "would you compromize your pg/vg ratio and/or nic level for pre-steeped juice". As a vendor, it doesn't cost them anymore to make a juice and pre-steep it, but it does create a problem if you want 73% pg 27% vg at 13.8mg of nic and want it pre-steeped. If we start demanding pre-steeped juices we are probably going to see less ability to customize our order.
Personally I'd like the option of ordering either. In nother words, give me the option of ordering JuiceXYZ at 18mg 50/50 pre-steeped, or I can order it and customize the ratio but it will be unsteeped. I don't see this being a big issue for the vendors as I'm sure, as an example, HHV has sold plenty of Gandalf at 50/50 or 70/30 at 18mg. I can't imagine they'd be worried about having to throw away part of a 500ml batch two years from now if they mixed it up at those ratios. I'm quite confident it would sell well before it would expire. For the life of me I can't figure out why the vendors haven't started doing that already.