First time poster & boffin not pilot, so be gentle
Long-ish post too
I'm a systems guy nowadays but was once educated in the dark arts of the 'future concepts' bit where you come up with an aircraft configuration.
There's really only two good reasons to build a high wing aircraft, and they're not mutually exclusive
1) Cargo handling/ground access to the fuselage
2) to put the engine intakes clearly out of the way of FOD (note intakes, not props)
Cargo handling covers both putting the floor near the ground handlers and making a nice big rectangular box. Most high-wingers have the wing cutting through the fuselage where it's otherwise too narrow to be of use to the cargo area.
So for pax aircraft, you do it because you anticipate operating places that don't have airstairs or other heavy support equipment. The SLF can get on & off using only what the aircraft brought with it. There is a side advantage here that the turn-around time is reduced, since you don't have to wait for any outside kit to move about - so you save a time on each turn around. I'd guess that's why the ATR & Dornier x28s are high up - I'm not aware of them being rough field capable but haven't played with them.
(Aside - that's why most biz jets are rear-engined, because otherwise the ground clearance would be so high, kit would be needed to get the Pax off - but the drag penalty of a high wing is too much)
And FOD - on a high wing, the fuselage can be relied on to block all of the nosewheel debris & spray. With a low wing (wing-mounted or rear engines), you have to assume likely spray & debris weights - and paths - only as far as the regulations say you do. A high mounted engine means that's not an issue. You've only got to worry about the engine sucking stuff up directly.
There's only a small lift benefit from the high wing, a big drag penalty - doubly so at >Mach 0.7-ish & it will always weigh more than mid/low wing, so you need a distinct operational reason to want to pay that. With the same engines, you can almost always make the low wing have better field performance for a given range-payload than a high wing due to structural weight.
Any stability benefits are secondary - you don't configure the airplane to make the flight control guys job any easier.