Why?
Do you think a majority of the people that buy the pc version already own the game on last gen and next gen console as in most people buying the pc version are triple dippers?
Why would it be crazy? Is the same thing said when companies allow crossbuy?
I really hate the idea that PC gamers should get this game for "free". It's insane, you want something you pay for it, period. If there is one thing I can't stand it's entitlement.
Cross-buy makes sense when in the same ecosystem (PS3 - PS4 - Vita, or possibly Xbox One - Windows 10).
I don't think a majority of PC gamers buying GTA 5 have played it on consoles, and I don't see anything wrong with charging full price as well.