RISC was never just about compiler and hardware simplification for improved
performance of the most frequently-executed instructions. It's also been
front-and-center in low-power (e.g., mobile) and embedded (now including
Internet of Things) applications, which each far outpace the number of
devices produced for traditional desktop and top-end computing
(high-performance computing, originally aka supercomputers). It's a big
reason why no one is using Windows Phones, or IoT components based on
x86/x64 hardware today.
Microsoft and Intel made big bets on their accumulated legacy code and
hardware bases being shoehorned into everything imaginable, with what
should have been obviously poor results for most of the application areas
pursued. Anyone remember trying to run Excel on a Windows Phone with
largely the same mess of menus, submenus, subsubmenu items, dialogues,
etc., as on the desktop version? IoT devices like door locks don't need
scads of registers, instructions, caches, etc., and can you imagine an
Apple or Galaxy Watch with cell capability running on a multicore x64
processor with a battery smaller than that for a vehicle?
A Blue Screen of Death is truly fatal for a product that depends on an
embedded device, like an ATM in the middle of dispensing over half a grand
in cash, a DVR in a satellite TV receiver that requires upwards of ten
minutes to restart and get back to where the viewer was (minus the
permanently lost live recorded cache), or a self-driving vehicle at any
speed above zero. Yes, BSoDs continue to happen when memory runs out
before users run out of things they want to do all at one time. Windows
systems can still routinely get to the point where it becomes impossible to
dismiss a modal dialog, close a tab or window, bring up the Start menu or
Task Manager, or other critical user interface element actions that should
always be instantly accessible. This lack of attention to user experience
is endemic to the Wintel way of doing things, going back deep in the
estimated ~100 million lines in their code base.
The x86/x64 instruction set complexity hasn't been helpful in reducing the
security vulnerability of software running on those architectures, either.
The multiple parallel pipelines that make possible speculative execution of
a number of branches before associated decisions are computed, have
resulted in the whole new class of security vulnerabilities such as
Meltdown, Foreshadow, and Spectre. This isn't limited to x86/x64, however,
as the most recent multicore ARM processors have also fallen victim to such
issues, they've just been late to the game as the most advanced (and
complex) features have been pursued (somewhat for me-too marketing
purposes), so fewer families/generations have been affected.