Nuts said:
Really there should be some compensation for that.
Possibly, but how much is the correct amount, as until you come to sell you haven't actually made any loss to be compensated for.
e.g. if you sell it immediately and have to take £2k less due to the accident history, then I'd say you'd want £2k compensation. However if you keep it for 10 years so that it's only worth £2k, then there may be only £50 difference between your's and an undamaged one and so only £50 difference.
The other issue around this sort of compensation (which rarely pays out on run-of-the-mill cars, and more on agreed value policies) is how do you prove you tried to sell it properly and didn't just take the first crap price you were offered, with the thought that you'd be able to reclaim the difference in compensation.
It's not nice, but I'm sure the majority of cars (in general, not just Z4s) will have had bumps & such, and some will never have gone through the insurance. So a buyer could buy a bent car without any inclination that it's been bent.
Look at the amount of wheel kerbing there is - that's not just affecting the wheel, but also possibly suspension arms, bushes, bearings, etc. - but once the wheel has been refurbed, you'd be none the wiser and wouldn't even think of mentioning it to a potential buyer.