The legacy compatibility is very important for microsoft’s enterprise customers, many of whom are still using some legacy software for aging machinery. A lot of big businesses are slow to move away from legacy software because it always incurs cost. Often they will tell microsoft and other companies they buy products from that compatibility is essential. They won’t invest thousands or millions of dollars to upgrade their aging infrastructure simply on microsoft’s insistence with their new product.
This is true and might be an argument that windows 11 is actually is moving away from its archaic foundations, slowly. But hardware isnt always a limitation. Companies will refresh laptops and workstations with better hardware yet still require use of legacy software. Its a tug of war between a companies financial spending, want for the latest tech in other areas of the company, tolerance to security vulnerabilities, etc. If microsoft tells them that they cannot use their essential legacy software on windows 11, and drop support for their older versions because of their own financial review, then they risk losing their largest customers.
I do think the legacy bloat is more to do with its foundations in software, being based on windows NT, moreso than legacy hardware. And with hardware improving, software gets faster for free just by running with more overhead. Its led to an inefficiency boom which you can see with games becoming less optimized because they dont need to be. Same could be applied to window’s with respect to new hardware.