I am currently playing a character with just this sort of construct. Every power he has is on a "slow" multipower of some kind. (He's a spellcaster, if it matters...) And having to burn time to switch slots is a limitation. My character is a speed 5, but this limitation effectively reduces him to closer to a speed 3-4 because of the time he loses every time he wants to change slots (which happens frequently). Sure, if the character never changed slots it'd be less of a limitation, but I end up changing slots quite a bit. And every time I do, I lose a move. A lot of the time I have to juggle whether I want to take the time to swap slots or not. Just last game I ended up getting clocked out cold because I was in a situation where I didn't get the chance to change slots because I had to recover from knockback and couldn't afford to spend the time. So, while I'm taking the minimum limitation for the loss, (-1/4), it's definitely making a difference in my charaters actions. And "If a Limitation applies to every slot in a Multipower, that Limitation applies to reduce the cost of the Multipower reserve".
And seriously, if a player sets up a construct like this with the express intent of never changing slots, then the problem is not with the rules, it's with the player.