Assuming that only highlighted skills are important for a given player, wouldn't it be beneficial to limit the number of highlighted skills?

Fewer highlighted skills would result in ability to focus only on those key skills in training, and hence the average value of highlighted skills would increase faster when there are fewer such skills.

Obviously the squad/player would be missing out on the flexibility that multiple position players provide, however quality-wise the team would benefit.

As a side question: are overall stars important or it's just misleading depiction of a player's true ability?

e.g. would you rather have a 6* rated player with 100% in all skills, or a 5% rated player with say 130% in highlighted skills and 50% in grey skills?