maybe because..
people like collecting games..
and backing up you can have the whole set of.. game
instead of a 1/4 of games you will have if you get them originals..
like you said.. itīs ok.. that they r cheap..
but..
10+10+10+10+10+10+10+10= lot of $$$
backing up more cheaper..
plus you have a little of fun modding and all that stuff
it depends on the taste of the gamer.. and people..