Piracy on consoles is hard enough, but you are now dealing with non-so-popular optical discs. With PS2 and X-Box, you need to get a modship, etc, etc. to get burned games to work. You also need to burn the media specifically, and sometimes the media is in DVD-format, such as GTA, so you need a DVD-burner. It is a long process and a very risky one, a lot of the times a person messes up his/her console just by trying to install a modchip.
These things won't make much of a dent ot GC for two reasons. It is one hell of a hassle and a risky one. Two, pirating optical discs is much more difficult than normal CD's and dVD's.