I know it was often the case in 1.0; AoE'ing down a large number of targets every minute is not a deep or fulfilling way to level. Not when you'd almost have to try to get yourself killed. There's nothing wrong with finding a decent concentration of things to fight, but aiming to fight one at a time due to how long they take to kill.
This heightens the importance of pulling; hopefully some interesting but fairly simple linking mechanics would have it require more concentration. Battles that last more than 15 or 20 seconds allow for enfeebles to have greater effect. That goes for both you and the mob(s). Sleeping something that linked could save a wipe. Or if you've been in the area for a few hours and they're dying faster as you've leveled up, you could strategically link or aggro an extra to save time.
Saying "SE knows best" is not a valid way to back up your argument. In fact, they knew 'worst' a couple years ago, and you'd have to be someone like Warlock to blindly believe that every decision they make is the right one.
Open world grinding provides (if you can't improve on what has become the standard fare of MMO questing for EXP):
- Easier and extended opportunity to socialize
- Greater understanding and appreciation of each zone
- Extended exposure allows people to fully understand the mechanics of a mob type
- Deeper fights as requiring more players can also mean requiring different jobs
- Allows for undeniably better quests
Also, I'm curious -what is the purpose of all the thousands of open world monsters if we shouldn't kill them for EXP? They're just window dressing? Something to look at but never interact with? Seems odd to only attack mobs that appear out of nowhere, instead of the ones that are actually present the entire time, don't you think?