There's close to 100 different rides that can be skinned now, that's up to 1500 skins that can in theory be done. Think how many resources that takes. There's HTC's bandwidth plus the load on players' systems if they try and use all of them (tech support calls to Skuzzy etc.) Then there's the administration that has to be done, checking and filing them. IIRC the last time this came up someone from HTC reckoned they might have overdone it a bit at 15 skins per ride.