Do you want a computer architecture that replaces and obsoletes everything you've previously learned or one that evolves and adds new features on top?

Either depending on the situation.

Then you are obviously running OpenBSD on ARM.

In that case you should probably not look at x86 at all. It's one of the most convoluted architectures out there, especially because it lugs all of that legacy stuff along.

When people say "who cares?" they generally mean "what non-vanishingly-small percentage of people care?" and I think that's still an unanswered question!

It very similar to chip die space - modern technologies are so complex that to learn how 8086 works is a very small effort compare to learning how the latest intel CPUs work. And emulation of older generations is a small part of this complexity.

I'd argue that 16-bit mode is conceptually more complicated than modern 64-bit modes, at least for userspace. 64-bit mode has a single flat address space (FS/GS are just opaque offsets into this address space), memory-mapped I/O, and a single system call trap instruction. 16-bit mode has segmentation, I/O ports, multiple trap instructions (and call gates!), address space wraparound...

Learning useful things is fun, learning useless things is unpleasant, so in some sense it's more effort.

While working on not always pleasant stuff at paid job as a hobby I sometimes learn 'useless' stuff from the past. For me on average old technologies looks simpler (though not without quirks) and more interesting to learn while modern ones often look over-complicated.

Just to clarify - I don't think that Intel should retain 16bit mode, but don't think removing it would make a big difference.