I for one actually enjoy the ridges. I see them as encouragment for a spin shot. I say that because the ridges prevent the bakugan from tipping on a spin roll and as SM said a spin roll is the best way to get a stand since the magnet's always facing down.
V, when i brawl you you NEVER spin roll. Also, if you dont have an exacto knife (like me) you can use sandpaper. a lot cheaper and easier to get.