Yes you can scrape old wax off plastic foundation and reuse it and they will draw it back out, but what if it habors a disease from say a dead out and you start a new hive with it?
OK, I agree with most of what you say - yes the bees probably prefer wax to plastic. Until it is drawn out, and then they don't care.
But I do not agree with the quote I cited. Of course you shouldn't reuse frames which contain virulent disease organisms - the kind of foundation is not the issue, the disease is. Do you automatically burn all of the comb from every dead out? If not, then what are you even trying to say? If you do, then you are the lone ranger I think.
Did you ever see
wax foundation in a feral hive?
In your own words
"Throw plastic foundation in the fire, replace with wax foundation, problem solved." One Problem solved, but then again in your own words
"Wax foundation needs to be cross wired to keep it from rippling,bees will eat holes in it if nothing is coming in (in a dearth)" So you just swap one set of problems for another.
Seriously, I don't care what kind of foundation anyone uses - I've given all three good solid trials with at least a hundred frames, and they all work, they all have their advantages and disadvantages. Everyone just has to decide which of those factors is most important to them. I guarantee you that once I decided I prefer plastic I didn't throw my stock of wax foundation and foundationless frames "in the fire." All still perfectly good - and in use.
Whatever you decide is right for you does not automatically make the alternatives inferior just because YOUR decision is made.