To the OP, believe me if you flew one this mystery would be solved for you. Look at it this way, take your typical executive jet, meant for what 6-10 people, now shove seats for 40-50 people into it and fill to capacity. They are cramped, noisy, on some airlines the seats are very worn and feel like you are sitting on the metal, the windows are down around your belly button, the sides are curved so you cant sit upright in the window seat.

There are benefits, quick loading, quick turn, gateside baggage check, only 50 people.

But they are just a tough tough ride and the airlines are using them for longer and longer flights.