If they doubled the respawn timers I don't think there would be any issues. While I haven't had many problems with this in regards to navigation yet (mid-40's), it has made farming in some locations a bit tricky solo.
Granted, the art of mob-dodging and gettting rekt by ranged/magic is something I've been used to lol. 30s seems a little excessive, though. 6-10 would be just enough to slip by while not killing the respawn for party grinding. Also understand a high respawn will hurt high level parties because the concept of pulling mobs is basically going to disappear given the changes to ranger.
A lot of this still circles back to forging and refining costs, though. Given the ability to actually make good gear, I don't think this would be much of a problem if the monsters weren't two-shotting people.