What would happen if British actors were used for English dubs rather than Americans?
Then dubs would move from sounding the majority of the time like a group of whiny kids with the occasional outstanding performance to actually sounding like real people.
Seriously, most US dubs (there are exceptions, anything Disney does will usually be excellent, Hetalia has a fantastic dub etc.) just seem awful to me, whereas the few anime that have received British produced dubs have been dubbed brilliantly.
I know this might be a bit of a European bias against the states showing through from me, but I do seriously wonder how many american anime voice actors manage to take themselves seriously. So many of them make characters sound prepubescent when they most certainly aren't, and I find that really jarring, even more so than the amount of jar I get from seeing JAPANESE PEOPLE SPEAKING ENGLISH in dubs of anime set in Japan.
This isn't an outright criticism of american voice actors, the US has some of the very best, it's just that the majority of said cream of the crop go where the money is to work on American produced animation (which isn't something I'd change, the quality of the voice acting in Adventure Time, Futurama, Ed, Edd, 'n' Eddy etc. are all up to the high standards of said shows and fit in perfectly.), while more niche animation and productions which were originally in a foreign language get lower budgets and 9 times out of 10 lower standards.
I do also find that the calmer, yet highly expressive tone of Japanese is more suited to a large number of anime than the louder nature of US accents, whereas Looney Tunes needs that tone.
At the end of the day, I prefer subs over most dubs, and american accents can be a little excited for my European tastes. That's just personal preference.