The mask issue is definitely a problem, as some people seem to think they provide greater protection than they actually do, whilst for others they raise anxiety levels. I detest wearing them for the reasons already mentioned, and would simply retreat indoors again if they became compulsory in any additional settings.
Few people were wearing them when I was out shopping, and those that did seemed to be constantly pulling them up & down or otherwise fiddling with them, whilst others only had their mouths covered - all of which would seem to defeat the objective. I also observed that, bizarrely, those wearing masks had a greater tendency to walk straight past the hand sanitisers.
The latest estimates are that approx 1 in every 3,900 people is now infected, so to introduce compulsory mask wearing some weeks after the easing measures would, I feel, increase people's concerns about safety rather than provide any reassurances to those who are already uncomfortable about the level of easing.
It's a difficult balance, as what A may be happy with can feel too risky for B, and what B is comfortable with may feel unbearable for A. Ultimately I think they'll have to go for whichever increases footfall.