But there's a false dichotomy here which is annoying. There's no reason you can't run an event and say "You can run proxies but they have to be legible." For me, the best proxy is a computer printout, on a plain piece of paper, cut out and put in a sleeve in front of another card. I use these for testing and for lower-key paper events. There's never any confusion, and when effort is taken to print the image out at the right size with the right sized border, bystanders and opponents rarely notice I'm playing with proxies at all.
So this brings up the argument of what is the difference between a really good proxy and a counterfeit. Since we are not selling the proxies we can put the discussion of morality/ethics aside, but once again going back to the OP why would WOTC enable this? Why would we buy cards from them if we could just print them out?
Yes, I agree there needs to be a standard for proxies if you intend to use them, I just don't think you should use them. There is no other format where people are clamoring for this, even though there are some decks in legacy that are now pushing up against the edges of vintage prices and quite frankly, affordability is subjective. Hell, standard is mostly more costly than vintage in the long run because cards are replaced so frequently and tend not to hold value, but no standard players are asking for a break.
Once again, sanctioning and coverage are the only things that are at all different here. WOTC would not sanction a proxy event, nor would they broadcast one where you can see fake cards on screen. If you can deal without those 2 things then you already have all the ability to run proxy events with whatever criteria you would like to have them in.