There's nothing inherently wrong with time pressure as a mechanic. However, the current implementation leaves something to be desired.

First, there's no precedent for this sort of rush to the finish mentality in the entire series. The dev team talks frequently about capturing the Final Fantasy feeling, however, armor design isn't enough to do this. Dungeons in Final Fantasy are about exploring, completing puzzles, finding treasure, and defeating bosses and mini bosses. I can only think of a few cases in the history of the series where I was forced to rush through a dungeon.

Secondly, it shouldn't appear in every dungeon. It's perfectly fine to build certain content that features a time pressure mechanic. Say what you will about FFXI, but having various "types" of raid content was a smart idea, that allowed players to pick a la carte the type of content they wanted to play.

And last, when it does appear, it needs context. Why do I have to complete this in 30 minutes? (A magical chest only appears if so is not a reasonable explanation.)