Personally, jumping and swimming doesn't appeal to me in MMO's. It looks ridiculous.
I'd personally rather have geographical barriers built out of ledges and water lines and keep the zones looking realistic and in tact.
It's only become an annoyance in this particular game because random ledges and barriers were placed in the middle of the playing field for aesthetics and has hindered player travel. The map revisions should be without such an issue so I see no need to have bouncing and splashing characters everywhere.