Some bugs are tiny and insignificant, such as a unit using the incorrect voice.
Sure, it can get annoying, but it doesn't really affect gameplay. Usually, these bugs are easy things to fix. There are, however, other bugs that have a large impact on the way a game works. StarCraft has had some notorious bugs, which were around for a long time, like the Command Center bug up until 1.04. It gave you the ability to liftoff your Command Center and move it right up close to your minerals, which allowed your SCVs to deposit minerals much faster, therefore giving you a great advantage for the entire game.