There's nothing in the Change Logs, so ....???

Very expensive to be update !

Personally, I wouldn't mind getting the update -- it's cheaper than it was a few weeks ago, and it's been a loooonng time (longer than most CC staff have been with the company!) since I first got it, but not "sight unseen" without more details. I'm hardly a professional developer and with the likes of Atom, Serris, and Sublime (etc) available for free ...? Even with these others freely available, it could well be worth getting, but tell me more, tell me more ...

Maybe it's an UPGRADE rather than an UPDATE

Must be an upgrade, since we have to pay for it. But I haven't found out what has been upgraded yet.

can't be anything too remarkable, they haven't added anything worth remarking on in the Change Logs. Surely they would have done that if they wanted to market it to existing users. Probably should have been added to the Version 15 series, Seems to be Build 808 which isn't far along, must be just a minor bug fix.

It seems to have been upgraded with some css grid parameters. It's very little, though, but I'm not css grid savvy enough to decide if more is needed or not. I haven't noticed other changes. E.g. I haven't found any flex related stuff.

they desperately need to do more to make building responsive pages / sites easier - there're just too many free / cheap online / offline bootstrap builders out there; and for the same price, but without full project features (but you can pay extra for them, and for working with WordPress themes) there's Pinegrow, which is multi-platform, and works with Atom. A lot of people here come from not-for-profit agencies, and the price for more fully featured Pinegrow is then the same as CC -- CCs got some stiff competition out there. Let's hope they haven't shot themselves in the foot.

cant get much easier that RFF or RSD

as usual, you miss the point, there are things, or ways of doing those things, that diehard old coders prefer to do by themselves -- after all, isn't that why the Editor exists in the first place?
so, please save us your "humor"

one of the best things about CC in the old days were the forums, but with responses like yours,
those days are clearly in the past