I think the important aspect this game needs to nail is feeling like Dragon Ball. Which means speed, mobility, and misdirection. From what we have seen so far, it seems like they have captured that kinetic rush.
The trappings, things like fusions or beam struggles, are superficial. Sure they may be cool once in a while, but they don't add much more than a nod. You don't want this game to be bogged down by this sort of thing. We have had lots of Dragon Ball Z games that try to cram this stuff in and they never get the feel of the series right.
Open the door up to that level of reverence and we are going to see the darkest side of those requests, where people want the game to reflect the power levels accurately... *shiver*
That being said...
I am okay with beam struggles, but only if they are incredibly uncommon clashes that occur when two people use a beam attack of the same power at exactly the same time. Make it a meter wagering system where the bigger wager wins. This way you get the nod, but it is a largely unobtrusive mechanic. Though, at that point, you have to ask if it is worth the development team's time.