It bothers me that the vast majority of this thread is either 'pro-jump' advocates poking fun at their 'anti-jump' equivalents as they continue to straw man the arguments to suit their cases. Why is this argument so black and white?

As it stands now, FFXIV is sorely in need some form of 3d movement, even in it's current maps supposedly not designed for it. People have already mentioned the "teleport slide" that occurs on traversable inclines and bemoaned the lack of an ability to drop from small ledges.
Personally, I think what FFXIV really needs is a "fall" in order to solve the sliding issue. Even many 2.5d games from the 90s had falling, and they didn't even have real 3d maps! If those physics come as a result of implementing an unrealistic jump, then I am ok with that. As far as I'm concerned, the argument of 'jump spam' is hardly worth it's weight considering the potential of spamming any other facet of MMO chat or interaction (emotes, yells, whispers).

On the other side of the argument, I agree that the alpha jump shown by Yoshi-P isn't consistent with the style of FFXIV, but again, this is an alpha animation. I'm sure with enough people mentioning the height and animation issues, it will be tweaked before final implementation.
IF in the event it is being considered simply as a cosmetic feature (which goes against almost every person advocating the idea), then there would be cause for alarm. However as a physics feature, the potential for gameplay variety in instances in the future is enormous, and duly welcome current maps with 3d issues.

For those who are wary of immersion breaking, perhaps you should consider the feature's potential as an immersion supplement. I feel stiff-sliding down hills and running at small ledges are infinitely more immersion breaking than a couple of Lalafell "bunny hopping" through Ul'dah.