Technically he wasn't dropped. Sakala was given time off due to the birth of his child. Although I agree with your point.
Beale even said he'll use Sakala in the games where he can use his attributes, when teams attack and leave space in behind. I think fans just see players being dropped and don't think of the bigger picture. Beale will rotate the squad to get the best of the players attributes depending on the team we face.
Cantwell will play against the teams who will defend for their lives because we'll be able to unlock defences.
I think the only constant will be the the centre backs.