One preseason game seemed like a mistake. One team has to travel, and for what? Think any starters would even make the trip.
Now instead of spending time getting scrubs and back-ups ready to play 4 meaningless games and the travel involved, the team can focus on scrimmages, extra practices, and film study / playbook time. I have a good feeling McVay and the position coaches will know who's ready and who's not and be able to sort out position battles. Also, less chance of preseason game injuries and the inevitable 'release with injury settlement'
I have faith the Rams, and yes the rookies, will be ready to play if the season actually happens. The Rams starters haven't been playing the preseason for the last 3 years anyway with good results, now everyone's in the same boat - let's see how they do.