Why is it that some of the smartest groups of people, scientist and engineers, are the ones pushing metric system because it's so simple?

While simpleton's, like me, just know instinctively that if a 7/16" is a little tight I need to go to a 29/64"

Not many tool kits have 29/32" wrenches, or drill bits, and most stores don't sell nuts or bolts that size. It's a lot simpler it the only wrenches you need are in whole numbers like 8, 9, 10, 11, 12mm, with no weird fractions like 29/64 or 15/32. Plus numbers are easier to add and subtract when they aren't fractions. Half of the time people use decimal measurements instead of fractions, and if you're going to convert to decimals anyway, why not use a decimal system to begin with, like metric? When you want to change from one unit of measurement to another in metric you only have to move the decimal point, instead of dividing by 12 or multiplying by 36, etc. You don't need a calculator to do it, and the only thing you need a pencil and paper for is to move the decimal point, not long division or any other such nonsense that a lot of people can't even do. And no converting "standard" measurements to the worldwide standard and back, introducing unnecessary possibilities for errors that sometimes have disastrous effects.

If a 10mm wrench is too small, I try a 12mm. I don't have to worry about whether or not there's anywhere on the planet I can get a 10 29/64mm wrench, and at what cost, or how long it will take to get one. If 10mm is too small and 12mm is too big, I know it's 11mm and not one of 128 sizes from 10-12mm 1/64mm increments. Unless it's something made to the "English" measurements, which the English don't even use, with a metric label slapped onto it like 1/4" hex head screws that say 6.35 or 6.4mm on the label.