I think you answered your own question, he came out because he was assured of playing time. I don't know a player who wouldn't prefer to be on the ice vs watching.

No one is assured anything. They are given an opportunity. If Tkachuk didin't produce he'd be in the AHL, much like many of the Bruins prospects who are sent down.

Back to the initial question...I would say playing is preferred. You only get better by playing, and you only have so many years of peak physical ability. If you are good enough at the lower level, you should be able to turn heads and earn an opportunity to move up. But need to be on the ice to showcase your talents.

At the risk of meandering down that rabbit hole, this reminds me of the EHF/E9 debate...third liner EHF elite or top liner E9, which is better (my son is on the younger end of midgets, so fresh in my mind). As above, I think maximizing playing time is the best play.