Originally Posted by figment 
They released GTA4 like 6 months after the console release so sales were probably weak on PC just because most bought on console in the meantime. Add on piracy and they probably really don't think of PC as a first class citizen anymore.
Yeah AND it was a crappy port, which was a slap in the face. They did patch it into some sort of shape over time though I guess which is better than nothing.