It's actually surprising the amount of new tech in a regular toilet - even compared to 20 years ago. And that's not a complex automated toilet, just a standard UK crapper.
Close coupled cisterns have been around for over a century.
The ball cock redesign is a result of the dual flush arrangement (I thought?). But yes that is a change.
Having never come across a soft close lid on a toilet I can't agree they're anything close to standard, I'm sure they exist though. (I'm British also btw, so our experience should somewhat match)
So that's one change mandated by law?
You raise a good point about Japanese toilets though.
That's interesting, high cisterns (with a chain!) were still common, when I was younger (80s) these were replaced by low cisterns with a pipe between. In the last 2 decades in the UK these have been replaced by close-coupled systems IME.
Re weight, firing is costly, you can improve the shape to reduce the mass of clay which reduces firing costs considerably. I've taken out 50 yr old toilets and fitted new ones.
All the recent commercial fittings (ie in businesses, or in domestic settings done by plumbers) I've seen have been soft close & removeable. There's still a bug IMO, they need some sort of arrangement to make them lift quickly but lower slowly, or soft close only at the extremes of travel (soft close drawers have it, so I guess it'll come; probably a price issue).
The toilet cistern ball cock has changed twice AFAIK, once to accommodate the dual flush (central column), and again to alter the hinging to improve the pressure applied at the valve and reduce leaks.
What were we talking about again ...
My toilet has a cistern, u bend, and all the features of a toilet of 100 years ago. Never the less toilets are far from dead.
What you are describing is a mature product, not a dead product.