I just don't understand how January-March is supposed to be better than November/December, as far as that goes. Same goes for spring training really (or spring college football which is only at the FCS level now). Hopefully we're further along in terms of testing, treatment, contract tracing and, ahem, government oversight, but it still won't be fast enough or widespread enough (ditto vaccines). Who knows if we'll even make it through the NFL playoffs or College Football Playoff as things currently stand.
But in the NBA and NHL's case I think it's simply that they need a couple of months off. A January 1 start means things rev back up after Thanksgiving, which is practically around the corner at this point. Players need rest, teams gotta do business.