Mainly, some techniques are supposed to be strong. Drawbacks are to balance a move, but that doesn't mean the drawback has to fully balance it, 50/50 is good for supers and maybe power ups, but a technique meant to be strong, has to be strong, even 55/45.
So, something like an Ultimate, or also some power ups, should remain good and reliable even if the drawbacks balance them, never make it in a way it will make you say "yeah ok it's strong, but is it worth the drawback?". Doubts are fair, but if the negatives even the positives, it's only gonna be an ultimate in terms of power, and that can work, but it doesn't mean you can't have slight more positives, SLIGHT.