>As long as people are using high level programming languages, what does it matter if the underlying cpu architecture is a bit of a mess? What actual difference does it make to end users?

A bit of a mess is an understatement. Think about it. Does the engine in your car matter? No matter how you slice it, you're looking at problems if your engine is dreck. Look at the AMC Gremlin if you want an example. It sold well enough though and was a money maker for AMC.

To be clear I'm not a fan of PowerPC either due to lack of active desktop development.

I'm a proponent currently of SPARC64 and MIPS development as both architectures embody what I want in a computer: Low clock speed, legendary reliability, active desktop development and efficiency. Sun/Oracle hardware may be pricy, but its snappy and reliable for its age and I have never had one die on me, plus theres plenty of them. MIPS I like for the same reasons, I own SGI desktops, there are Chinese made MIPS desktop systems which have open documentation and are relatively inexpensive.

ARM has mostly market in cheap DIY hardware which may or may not have good documentation, has closed firmware or else is extremely expensive by comparison. Id say ARM has a long way to go before I consider it worthy to SPARC or MIPS