They want to be able to blame non-compliance as a reason for continuing their authoritarian measures to "contain the virus". If everyone complied and the virus went away, well then these politicians and governors would no longer be able to play the role of mini-dictator with their constituencies. But if those "evil and stupid Trump supporters" continue to "deny science" and refuse the vaccine, welp then I guess it's 6 more months of lockdown because you all couldn't behave!! Mark my words, this WILL be their angle.
And as an added bonus, they can also use the non-compliance to pass more authoritarian (even downright dystopian) laws (edicts) that are aimed at forced vaccinations, thereby handing over a blank check to Big Pharma every year indefinitely.
This is why Democrats fearmongered the vaccine while Trump was in office. This is why we're actually getting to see stories in the media about bad/allergic reactions, or the Hank Aaron thing, etc. They WANT people to reject the vaccine. That way they can carry on with business as usual.
Democrats can't function without a scapegoat. Their whole platform is built on having a fall-guy.