I don't get that either? The Mk5 was anything but angular. It was all round, soft curves everywhere and a bit fat arsed tbh with that half painted rear bumper. The Mk6 was clearly more "angular", they put sharp creases on the panels where there were none before and carried that into the MK7.
I much preferred the front end of the MK5 though. In fact I think the MK5 GTI front end is the most distinctive of all the generations.
The rear lights on the early MK6's were terrible. Straight off a Toureag! But the LED versions in the later cars were a huge improvement.