I can see why we aren't playing a first choice eleven yet. We have a few injuries so you don't want to rush players back before they are ready. Plus getting the team used to playing the same system with different combinations of players makes it easier for the squad to adapt to changes in the season due to injuries and suspensions. Also, it means that the opposition can't scout you and prepare for playing you in the regular season as effectively. Finally, because of the playoffs it's more important to have fitness and form later in the season rather than earlier so maybe giving an easier workload to key players now is a way of trying to make them peak later in the season.
Obviously I see the argument the other way too, but I don't think it's as simple as "we should play our strongest team right now".