The owners are proposing 50 games because that would mean paying the players 30% of their salaries (rather than 50%). You might be right though, they may want to get through the playoffs as early as possible since playoff TV money is going to be huge for them and the 2nd wave might cause a disruption right around the time the playoffs would normally begin. Maybe a little bit of both.
A 50 game season would be good in one sense, as mentioned the games would mean more. If you start the season off terribly, even if you're the Yankees, then you're f***ed. If you start the season on a hot streak, then maybe an average team sneaks into an expanded playoff round. It does sound more exciting in that sense, and TV ratings might increase if each game means more. But for a game like baseball to have only 50 games, it goes against everything the sport is. I'm not a purist by any sense, the game has to change in order to attract new fans, so I'm open to practically anything, but 50 seems way too small, even in times like this.