Do not you see the useful !?!?
For me it was the first thing I suffered, since the UCAV deck appeared in this game.
I often keep the "attack enhancer + 25%" (which consumes 1 blue chip) ready to be activated (especially during PVP tournaments) ... in order to activate it in case the situation requires it!
But this means that I can not activate any other bonus (even those I would like to activate) because if I did, even if I left a free slot, I could not use this slot to activate the attack enhancer + 25% (1 blue chip) when the right circumstance would occur to use it.
So I have to decide:
either I activate all my slots to benefit of other bonuses (for 3h), but in this case I remain without the attack bonus if I need it during those 3 hours;
or I have to choose to have their activation always available; in this way, in case of emergency, I can activate the "attack enhancer" when I want (but I don't uses the other bonuses).
This implies that when I want to have the "attack enhancer" ready to be used when I want (often, during PVP) , then I have to give up the activation of all the other bonuses.
Vice versa, if each slot could be activated separately, I could activate all the other slots continuously, and keep only 1 slot ready for activation (the one intended for the use of the blue chip, in case I need to use it).