[@kishin asura]
The one minute time limit is to ensure that the ability is almost exclusively used outside of combat. If someone can just pop off in the middle of combat, then there's no stakes. Reducing it to a matter of seconds means that you could just hide around the corner and TP out, presumably to some dimension where you'd have a massive homeground advantage.

[@Teoinsanity]
Vehicles are probably much faster at moving from dimension to dimension. However, they come with the downside that you actually need to be in the vehicle in order to use it. As such, the time limitation is replaced with a place limitation.