Sod's law. You religiously change within warranty, the one time you don't, you get punished for it.
If you are after another Golf, chances are, a MK8 is going to cost you miles more than a MK7.5 GTI right now. Higher RRP, little or no access to discounts for the first year or so after release, and it looks like it's going to be a bit ugly vs MK7.5, just as MK6 was when compared with the MK5.
Now we've got to fund 2 cars in the household, we have 2 Polo GTI+. If my wife hadn't learned to drive, I'd have probably spent all the budget on an RS3.