"Should" in the sense that they need to provide basic dignity to people on board. Same as toilet and basic necessities like glass of water or very basic meal.
Although "dignity" and modern planes can't be used in the same sentence, unless you pay 5x for business class, passengers are humiliated less there at least.
Following your logic, it will be ok for you if airlines start charging for washrooms, reclining seats, windows or anything on board except just being alive. Why wouldn't you pay for washroom $15/minute + water and toilet paper?
Although "dignity" and modern planes can't be used in the same sentence, unless you pay 5x for business class, passengers are humiliated less there at least.