Going by other games, the actual distribution should be closer to 90/10, regardless of how good the evil path is. People just don't play evil even when they pretend they are evil characters. SWTOR has interesting stats about that. The Empire has the most players (and best stories), but 90% of them play light-sided Imps...when the quests don't always support it.
^This. And especially when you factor in that fans of the FR setting (even if they constitute only a minority of BG3 fans) are that much more likely to mirror the setting's favoring of the good side over the evil side.
