I think it´s okay, I remember one part in Brothers in Arms hells highway, where an Irish or Scottish tank commander talked to Baker and his men about how he´s gonna help him get through this "shithole"...he has such a strong accent that all the main characters are confused as to what he want´s from them, and shrug when he rolls off...
They also had a british guy in there who always kept shouting "You´re a lucky yank, Baker." and always had his british accent...it worked, because it FINALY showed that there weren´t only americans in the DDay invasion, and it was also quite pleasing to listen too, aswell as a good vehicle for jokes like the scene I mentioned above, which lightened the mood somewhat after a particulary gruesome firefight.
Also of course, that guy in Reach, with his scottish accent.
Now going to my native language, german, there isn´t any variety at all...all voice actors speak pretty much perfect high-german if they aren´t a joke character or in a comedy point and click game anyway, and it´s quite unnerving.
Sure, you wanna make it understandable for the general audience, but the original game, let´s say GTA4, also has Mexicans, Italians, Slavic, American, English, Asian, Texan, Deep-south, NewYork and what ever characters in it, all with their own accents.
And then the german dub would throw it all away (note that GTA games, and I guess most Rockstar games don´t get dubbed, just subbed, that´s why it´s hypothetical)...
But a game magazine said on this issue that in "Baldur´s Gate" you could make a bloke who talked in a heavy-saxon accent, which would be quite nice, actually.
I still remember the RE 4 merchant with his "whot´re you boyin?" accent...RE games also only get subbed BTW...
So, I´m all for it...and I think in RPGs, you should be able to give your character an accent of your choosing during dialog...it would require recording all the lines in the suitable accent, and maybe even with different people for different styles of voices, but it would be nice to hear...
"Oi mate, oi´m gettin nothin´ outta thays longsword mate...troi sellin it?"