Just remember that the AK is, and always has been, a mass production rifle, made in countries with inexpensive labor. So tooling up a press and fixture to press fit the front site block would be much more desirable than adding a 5 cent pin and bolt. And stamping and bending sheet metal, followed by welding on the rails (all done on purpose built machinery) is more preferable than starting with a big billet of expensive metal and making a big pile of chips on a CNC mill.
By way of comparison, if you live in Lancaster, PA and want to build a barn, you can go with 200 year old designs and a crew full of camera shy guys in straw hats, for short money. But if you want something new, and custom, with galvanized metal this and aluminum that, and no support posts every 12', you'll have to pay more for Anglo contractors to do the job.