Uncapped adjustments are more expensive to build and must have a lock if you for sure don't want them to move. Remember a lot of cheaper scopes aren't even waterproof without the dust caps on. SWAT guys don't want exposed turrets at all because they're not taking shots over 100 yards and don't want to risk inadvertent adjustment.
As far as .1 mill increments, one can only guess why not. Probably because the average guy at that pricepoint doesn't know what a mil is. He knows what an inch is and probably thinks it's the same as MOA and for his purposes it's close enough.

