Yeah, the real problem is having to balance the games to be a good spectator sport.
The double elim Bo3 format makes it that the series could potentially end after 2 games, which is pretty damn lackluster (admittedly WB advantage of one game doesn't fix this) and could instead stretch up to six. Bo5 would be even crazier in that regard.
So a single Bo5 is usually the best way to ensure a decent length while still keeping it in a reasonable timeframe.
I don't really like it, but that's the way it is.