I don't think its unfair to include the negative equity. Its part of the facts of this. Never had negative equity before and I have had at least six PCP deals in a row over last decade. Its a sign of the times and the misfortunes of VW :-(
Thats a loss on this car, shouldnt be considered as a "cost" of the next one. If your next one is a lease you'd still have to pay that £1500 equity, would you then add 1/24 of that £1500 to the monthly lease cost?
Unless they've got a huge deposit down, most PCPers wont be in positive equity unil 2/3 through a 3 year PCP or 3/4 through a 4 year term. Getting more than GFV at the end of a PCP in p/x towards the next one used to be a given, but it isn't now, there'll almost certainly be something in it, but not quite the 10% over GFV that we've previously been used to, thee hook now is the deposit contribution and loyalty discount.
If going forward this dieselgate issue doesn't blow over I won't be buying another VW and ending up with BMW residuals unless I can get BMW sized discounts.
Currently with the deposit contribution and loyalty discount, most of that poor p/x value is covered for anyone chopping in right now. When you give a car back early without another in the pipeline, you're far less likely to get a "generous" value, theres no hook to keep you as a customer. If you get a settlement figure for walking away from your agreement it'll almost certainly be a good £1500 less than the p/x value you'd be offered against a new one, and I think there is where the difference for you lies between this time and all the other times when you've got another VW.
When your 2 year p/x value is only a kick in the arse off the 3 year GFV, those thinking of changing will have to weigh up the extra discounts vs the crap p/x.
I personally think that VW overreacted in offering these bigger discounts and hammering their residuals. Their sales dropped 20% in the short term, they should have waited it out IMO - people still buy Toyotas after all those safety recalls. Most consumers care more about running costs than what comes out of the exhaust.
Expensive VWs are relatively cheap (monthlies relative to RRP) to own due to high residuals, without those residuals they are not good value for money. Damaging residuals with their big discounts will cause far more harm to their business model than freezing RRPs for a year. VWs car price inflation is crazy given the current economic climate.