Because of the additional homologation required for the US market and their predisposition for cheap-assed motors VW gently continued development of the Golf2 and sales into the US into the 90s. From memory they moved Golf2 production to Brazil and that's when things like the 2.0 bottom end, crossflow motor head on the 8V and bonded windscreen were added to the Golf2 US version.
Let's face it, if you have a bunch of panel presses and manufacturing kit that's not quite worn out, you might as well keep using them as long as possible.
Just look how long they kept churning out the Beetle!