1. You don't actually know who asked for a more dangerous field, do you? You just somehow think that those who asked for it, must be grinding FATEs in North Thanalan, because, "oh yes that would so prove my point!"

2. A more dangerous field generally adds to the sense of adventure during leveling, and that is for those who quest.

3. Heavensward mobs are harder? You've got to be kidding me. They just have more HP, that's all. They are even more spaced out than ARR and the fields are as easy as it has ever been. Mobs are still leashed to a small area and you still ride your chocobo through everything until you get to your destination, ignoring all the mobs. No mobs are not harder. They're still as easy as before.

4. You will out-gear and out-level everything eventually, so it's all about the leveling experience. Fetch quests are fetch quests because fields are not dangerous. There's nothing more than play fetch. A much more dangerous field with randomized patrols and dynamically linked packs with a huge, HUGE leash radius will turn those fetch quests into real quests, which in turn allows much higher rewards, removing the need for enormous numbers of mundane quests. Quests should be about quality, not quantity. But ever since the who-where-what framework was established in the MMO genre, quests have been nothing but mass-produced mundane to-do lists because you needed that quantity to boast that your game is better. Real dangerous fields let you focus on the quality of your quests instead of just the same thing with a different copy writing.

Don't get me wrong, people do enjoy the writing. But being a game that has combat at its core, there's no excuse to skimp on the combat.

TL;DR: I think the fields in Heavensward are not dangerous at all. They're bigger, yes, but just as trivial to explore and travel through as it was in ARR.