Tex, get ready for a good laugh....but I swear this is true!
The "engineer wonks" in the industry, in particular the ones involved in making the code, are of the belief that bare metal is best- you never know when you'll need a ground! Their attitude is, well, if you MUST paint it, make sure the paint can be easily scratched away by locknuts, and "while there is no code as such, we prefer grey, as it looks like bare metal."
There was also concern over intruding on someone else's color.....heaven forbid we paint it white (looks dirty too easy, hospitals like white), or blue (can't confuse it with water lines now!), green (that's only for grounds, silly!), red (that for fire systems, isn't it?), etc.
And many manufacturer's will resent your claim that they all use the "same ugly grey." In truth, several of them have gone to great expense to trademark slightly different shades of grey, so their gear looks the same, but is 'distinctly different!'
As for overall appearance, these engineer and lawyer-driven manufacturers are more interested in FORCING yo to use their products, than in appealing to your tastes. Thus, the non-standard components, continual 'tweaking' of the NEC, etc.
