Mask mandate or not, I have zero problems with a private business setting their own mask policies, as long as they are upfront about it and WDW is. I am by no means "anti-mask" but personally, I'd prefer if WDW went to masks required for indoors only, at this point. I understand, however, the logistics of why they haven't though. Americans (yes, I am one too) are, for the most part, entitled. Throw in paying $1000s for a trip and that entitlement gets brought out in a much more frequent manner. In order to combat this, WDW has to go to an all or nothing strategy. Making the CMs enforce these indoor / outdoor all day, would be a nightmare for them. This is 100% the reason WDW had to tighten the mask requirements in restaurants. I have no doubt guests took advantage of the situation and CMs felt uncomfortable being the mask police.
As said here by others, it's not just about the guests. WDW has to look out for it's CMs too. There's always been a ton of talk on here about supporting CMs during this time. Well this is a policy that is in place to protect them. Let's be honest, very few, if any, people will stay in their hotel rooms if showing symptoms after spending WDW kinds of money. So there are likely 100s of people there, daily, who can pass on the virus.
My guess is as the numbers, hopefully, continue to fall AND WDW can offer or help get vaccinations to its CMs, the mask requirements will be lifted.
We have a trip in November and I'd gladly trade wearing a mask a bit longer if it meant a faster return of things like (a revamped) FP, more parades, shows, fireworks and more restaurants being open.