I don't think it's that anyone here consideres the SI system dubious or suspect at all, it's that we use "standard" units because of tradition. Most people recognize that the SI system is superior, but since we grew up learning standard units, that's what we're familiar with and what we teach our kids. It's kind of a viscous cycle that they tried to break in the late 70's but were unsuccessful. It may happen in the future, but there doesn't seem to be any interest in it at the moment. It doesn't make any less sense than the English language or scoring in tennis so I don't really see any reason for us to change.
As Blake pointed out, too, most science classes teach in SI units and many technical fields (mechanics is sometimes an exception) are done in SI units as well. I'm not even sure if there are standard unit equivalents of many of the electrical units (voltage, current, charge, Teslas, etc.).
Personally, I'm very bad at estimating distances no matter what system they're in. I know I did a good job of putting the other day, but I honestly have no idea if I was hitting a lot of 30' putts, or just happened to end up 15' from the hole each time. It also means I only have a very rough idea of how far I can really throw.
Here's the site I use when I need to convert units: