Well, there was some reason they made up Eruption for Brawl, and they only have more reason to use it now, since not using it would be a moveset change...
In any case, if it's a bit more practical than it was in Brawl, then there really isn't a problem, in my opinion.
Sword beams are a nice dream, but I've always considered the possibility of Ike actually getting them to be rather unlikely. They're probably just too good, really... in Ike's games, after all, they're as strong as a close-range attack, so... how do you balance that? Making them weak would basically make them pointless, and keeping them strong just doesn't work. Avoiding them makes sense.