I think right now the motivation is safety. I seriously do and I'm a cynical person. In Flroida's hotspots in South Florida, they've asked the governor to expand mail in voting as well. With him being a Trump supporter, it's doubtful he'll break his allegiance with Trump to promote it. Florida's infection rate remains relatively high with 800 plus cases yesterday, but death rates are falling. In fact there's buzz Republicans would like Trump to move the convention here to Florida.
However, Florida has had mail in votes for many years and in fact one-third of voters took advantage of it. That's a lot of people and it hasn't proven to be a mess. So whether or not the governor pushes to expand it for safety reasons, it remains a popular option and one I think the populace will expand on their own.
The idea that Trump is promoting that people will be forced to vote for someone they choose not to is pure conspiracy and fear mongering. I still am not getting his motivation against it. With his "liberate Michigan", wanting large crowds to be able to gather at his convention, promoting church services as essential, his not role modeling mask safety, his motivation certainly doesn't seem to be safety.
I voted by mail once at the beginning but since my schedule has included Tuesdays off for many years I just vote in person on Election Day since it's just a few blocks away and I can go on off hours. I voted in. person in the primaries when we were first starting to hear about social distancing and they had some good measures in place, so I felt safe. But since then it has really spread to 50,000 people here. We also have had a voter ID law as long as I've voted here, nearly 30 years.
Here in Florida the demographic that seems be mostly continuing with safety and social distancing is the older population. This is anecdotal from own personal observations. This is a good thing because they are the ones with the most co-morbidities and The older population here is a good deal of Republican voters and vote in larger numbers than younger people. I would think Republicans would want to tap into this. My elderly (and Republican) parents in North Carolina are into week 10 of lockdown there and said they would continue to do so as their own personal choice, which I support and practically demand of them...let younger healthy people make their own choice as well. I haven't asked them, but I'm thinking they would want to vote by mail option if elections were held today.