I can see what you are trying to say, but I really don't think you're right. Yes, fractions are sometimes nicer with other subdivisions than decimal, but e.g. angles of a triangle: right-angled with 90 deg + 2 x 45 deg would be 50 + 2 x 25 deg. Works fine. Ultimate precision isn't necessary in everyday use.

The real reason why the US hasn't switched is that it is really painful to change something like this.