I agree with you that the art is totally personal opinion. But i think Skills and Abilities matter.
I am the type of Player not looking for the highest TP possible. In my opinion a synergistic Team is much more usefull in the long run. Of course in the current state of the game it's irrelevant but i am planning for Future Events and UBER Bosses. And trust me it makes a difference if your Girls buff each other with 80 % or more Atk or not. I mean if it doesn't matter later why did the Devs putting the Abilities in the game?
For example:
Why is Lilac's or Dipladenia's Ability so usefull in some Maps? Cause you have to adjust for certain situations to push your Squad to the Optimum.