We're obviously all biased, but I completely agree about the styling - such a great looking car design which works as a whole. I don't know why the Bangle designs get slated so much: at worst they could be called "interesting" but IMO it's lovely.
Would the 507 be highly desirable today if they had continued making it for another 10, 15, 20 years? No. So, for all of us that have the current Z4 why are you sorry to see them stop making it? I am glad the car is evolving. Look at the Corvette. It has gone through a number of revisions over the years. The C1, C2 and C3 are all very highly collectible and who can argue which is better looking?