You have to admit that while some principles are not arbitrary, there are definite design styles or trends that go in and out of vogue, and at the time everyone was convinced they were good design.
That doesn't mean they weren't. User familiarity is a big part of good design, so playing to the current trend may well make your thing easier to use.
For example, there's no reason why search boxes should have rounded corners - it's just an arbitrary style. But since users are familiar with rounded search boxes, using them could make your site easier to use.
There is no such thing as form. There is only function. Function follows function. Function informs function. So that what we see is a fractal of function, a function of function.
I'd also argue that an uncontroversial definition for 'good design' would be design that functions best for the majority of users.
That somewhat explains the trends you see in design, because when we employ a convergent design standard, it's more readily accessible in a single visit than a design that breaks away from current conventions.
It's also empirically the case that the convergent design standards represent the 'fittest'.
And I would argue that evolutionary speaking they represent 'good design' (that's my definition anyway).
The folks who designed those old amber IBM terminals (that I still use at work) would have argued that:
- Black background is easy on the eyes.
- The flashing cursor draws your focus.
- The amazing bold font technology breaks up the page very nicely.
So it would appear that "good design" is just a function of the technology available.