I'm not a big fan of free jumping, since it will pretty much ruin the atmosphere for me. People get bored quickly when walking from A to B. And to pass their time, I can already see the mighty Roegady and proud Elezen to jump around like madmen on their way to the next camp. However, that was probably said a hundred times before and there will be at least a hundred answers about how much of a lame and old-fashioned person I am, so off to something else:

If jumping is implemented and can be executed at any time, it should get some kind of downside. For example the jump animation could have less forward movement than running and thus slow players down. Or movement could simply be suspended for a short while after a jump. (Or each jump costs 25% HP! Haha!)