The point is, it just creates needless confusion. Even the Brits, one of the last holdouts, have largely shifted over to metric.
Not only does it make more sense (base 10, as you point out - not the less than logical nature of "feet", "yards", etc. in relation to each other), it is how the vast majority of the world works. It makes it difficult to read text made for an international audience (Wikipedia is a good example) and simply over complicates communication in a "global" era.
The reason it hasn't been adopted is the same reason we still have time zones. People don't like change. Time Zones have pretty much lived out their usefulness long ago, and countless millions (perhaps billions) of dollars wasted every year due to snafus regarding it (missed business opportunities, etc.) because it's such a complex system (particularly in the US, where local variances and such mean you have to consult a computer to really find out).
But people simply could not get their head around depending on when it's light/dark in your area, your "nighttime" could actually be between 0800 and 1600.
It's one of those things that isn't likely to change, but the reasons for such generally boil down to "I don't want change" or those delusional folks who utterly reject any system that is not US-based/centric as somehow a threat to our nation, because no one else could ever have a better idea or anything like that.