I'd like to touch on something that makes me a little bit mad about the grouping we all experience in Alpha 2.
As of now, grouping with too much of level difference than other party members is extremely punishing regarding experience loss and gear drops. As of now, the drops are significantly lowered if party members have 4 or more level difference, and the same for the EXP gain.
I think this brings an antisocial aspect in a game that is supposed to be social, mainly because we aren't at the same place in life. We can't always be online to catch up with our friends so the level difference can become suddenly very high. And no, it is not easy to find a party to grind at level 14 when everyone is 19+. I lost 1 hour and a half trying to find a party the other day. It was a big waste of time.
Now, I will say that I understand Intrepid's intent behind this decision, but I think they overcomplicate things a little bit when it can be a simple solution that works for a lot of MMOs (including Guild Wars 2) : Level Scaling.
For those who don't know what level scaling is, it's a concept that if you party with member with a lower level than yours, your level will be downscaled to the same level or similar power rating than your teammate. This effectively allow higher levels to play with their friends while maintaining a restrictive approach to level boosting as they won't be able to kill high level monsters because of their downscaled level.
Let me say that even if you're downscaled from level 25 to 10 (because your friend in your party is level 10), you would still have a little bit more damage/mitigation than your friend, because you would still have access to the skills you unlocked via your adventurer leveling. The difference is that you wouldn't make 100% or 150% more damage than your friend, but instead maybe 5 to 10% more (depending on how Intrepid balance this). With this level scaling, there wouldn't be any drop decrease because their power is similar.
This should only be a PvE situation. If the level 25 is downscaled to 10, it shouldn't affect their power against other players.
I have examples from Guild Wars 2 of how it works.
These are screenshots of my level 80 character with normal stats and normal damage on a level 80 monster :


These are screenshots of downscaled stats to level 9-10 and downscaled damage :
As mentioned above, my damage is 562 right now, but is it still a little bit higher than level 10 characters because I have access to a lot more skills and rotations.


This screenshot is the UI indicator that someone is downscaled based on the area (party in case of AoC) :

I'd like to mention that I would like level scaling to be only effective when in a party with lower level players than you. Not when you enter an area with lower level monsters.