Quote from TheOnlyOne652089 »Planeswalkers are supposed to be "rare" and very special.
Making them uncommon or even common would completely debunk all of that flavor, they just CANNOT do that to keep planeswalkers as a type credible.
The vast majority of "bad" planeswalkers could and should simply be enchantments that do the effect you would use the planeswalker for.
I do agree with most of what you say and you can argue that before PW cards existed, some Legendary creatures were highly sought after and others not so much. Now that WotC has precedent in down shifting Legendaries (in ONE set) to uncommon I do not think it's far fetched to see ONE set with uncommon PW cards. If I were to design an uncommon PW, I would have it as a loyalty of 2 or 3 max, with one or two abilities as only minus abilities. They would be purposefully designed to not stay on the board the whole game. You cast them, use their ability to help your cause, and then they go. I think it would still be credible, just not highly powered.