If they did jump as a move bonus that cant be used near enemies, maybe to skip some hard terrain and get some elevation. People wouldn't be super upset about it.
Jump could be a movement action or a bonus action very usefull to get out of surfaces or to play with verticality in combats.
The biggest problem with jump is that it is coupled with disengage and the second problem is that jumping allow us to move further.
Those 2 things wouldn't change the overall experience but it would really increase the "look" of combats (mario, kangaroo, frog), their tactical value and the consequences of our choices (less systematic free things to do at each turn).