I think it's more comparable to bemoaning Porsche releasing the Panemera (developing a family car from sports car, the exact opposite of what VW has done with the CSS) - With it's diminished practicality, the CSS is more of a track toy than the everyday all-rounder the Golf is supposed to be, the CSS defies the purpose of the Golf as a model. Out on the road, driving it in a lawful way it's practically no quicker than the standard CS which is effectively 290ps, because out on the road you will not run out of overboost when you put your foot down unless you want a driving ban. 15 seconds of overboost from a standing start will probably get you to 95mph, way more than you need to avoid the risk of losing your license.
It's no bad thing - pushing the boundaries during development helps tech filter down eventually, but for the majority of people here, anyone making the full use of the CSS will not be using it as their primary car, making it a truly niche Golf.
Hats off - I was thinking the exact same analogy with Porsche after I was done writing my post but it was already too big to add to it. VW and Golf started and built their reputation as great everyday cars combining top class practicality and above average build quality. A few more focused variants like the CS and CS-S are not enough to change that image. Much like the Cayenne or Panamera are not enough to make Porsche look like the default luxury family saloon/SUV manufacturer, although those cars have seriously helped Porsche to continue focusing on what it started and wants to always be: THE sports car manufacturer.
However, I don't think there would be much bemoaning if the CS-S was a full size Golf (even a 3door one) and fully "purchase-able". But the reason it couldn't be is the same reason the CS could not be the CS-S in the first place. The hierarchy had to be preserved. Which is all rather silly imo, as the R is still the only one offering 4WD for whoever that is no.1 priority. And it's already much less dynamic or rewarding than even the standard Clubsport. So no need to split the "driver's variant" (Clubsport series) in two... Still that's how VW decided it had to be...
And again, a one-off 400 limited 2-seater variant is naturally impossible to be of much interest to even the performance mass. It takes a great car that can also be bought at will and serve as a full car (not half one) at the same time, to really attract people's attention/interest and serve as a reason to party.