I do not need to miss Windows XP, because I use it as my offline OS alongside Ubuntu Linux, which is my primary online OS now. To me, Windows XP is the final true Windows. After Windows XP, NTVDM became broken (32-bits) or non-working (64-bits), DirectX was cut off to support only version 8 and above, native hardware accelerated audio was cut off, original WinHelp and DirectInput were cut off... You name it. 16-bit support has always been part of 32-bit Windows versions, but it may be gone with Windows 11. Windows XP has it all, and compatibility is lacking for only a small number of programs.
Windows 98 SE is still the best version of Windows, if thought from the viewpoint of compatibility; It can theoretically run every program designed for MS-DOS and Windows (not NT) from 1980 to ca. 2004. Those a few stubborn programs are possible to run on pure MS-DOS on 98 SE.
Many people blame hardware, but in fact the core compatibility problems lie within the operating system. If Windows 10, XP and 98 SE are installed alongsode on the most modern PC possible, Windows 98 SE and XP can still run the programs that are incompatible with Windows 10. For energy-efficient computing, we need to make a move back from emulators to NTVDM, as the Intel's processors can still run 16-bit code. Plus, NTVDM required about 10 times less power than emulation. Instead of dropping NTVDM, we should create a better NTVDM.