Metric is undoubtedly an improvement, and if there were political will, I'd be all for a renewed push to make it the sole standard. Cultural inertia within a single large and wealthy country is pretty much the only "advantage" the older "system" has over metric.

I do get a little bit protective when people suggest that Imperial/Customary/whatever is nonsensical or useless, though. It's more that it's disjoint and obsolete. Units arise out of circumstances, and shit like using 12 inches to a foot makes a lot of division into fractions really easy. Same with 8 ounces to a cup, 16 to a pint, and so on. Dividing shit in half or thirds is a pretty easy paradigm to do math in your head if you're not really getting a lot of formal education. Most of the base units ultimately trace back to something perfectly sensible for a pre-industrial society.

So there's method to the madness, it's just that it was a thousand different methods, arising from various trades and merchants trying to standardize (yet also retain) their traditional measurements for their own needs. There's not the grand unified system that only really became workable with standardized manufacturing and improved communication in the 19th century.

The other funny thing is that while units can and do still cause confusion, many US Customary units are literally defined in terms of SI and have been for well over a hundred years. An inch, for example, is exactly 2.54 cm, because even in the 1890s Americans knew it was stupid to try match a metal stick in London to one in Washington to one in Paris with any greater precision than that, and only the SI had a set process to refine unit definitions in relationship to natural phenomena.