I do enjoy how archery is different from the melee combat system. I love how aim bar simulates drawing and taking aim, with aim resulting in the hit chance and the damage made which is a clever way to scale damage based on aim with only one hit-box. I much prefer to have a physics based targeting system rather a fast paced auto-target card game so I really hope ranged stuff doesn't get integrated with the melee system. Although if there's a concern about latency (which I haven't really had problems with) that might be the "reasonable change" way to a solution.
General combat:
I see a lot of people saying it's useless in PvE. It's not. If you work your MS up and have a horse with enough juice to do some extended sprinting, it becomes pretty useful. With only light armor on it also becomes pretty fun. With high enough MS and a top q bow and arrows you can solo mammoths but if you get caught, you're ded. As a result every mammoth feels like a boss fight. And that's the thing - if you want to damage something at a range, it makes sense you'd be very vulnerable if caught. So at start I'd suggest putting major MS debuffs on heavier armor (some balancing required).
Which would also open market for leather based light armor and add some self reliance and economic relevance to hunters. But I'll try to stick to the topic.
Mobility:
Wearing heavier armor would make sense to mean having lower agility and agility would make sense to result in movement speed or stamina drain and would help with making archery or lighter fighter roles more interesting. But I guess that'd fuck with more than just the melee combat and I won't even go there.
There are probably a lot of ways to differentiate mobility of different roles. One way would be adding a micro-slowdown dependent on the percentage of hp lost on a hit(Analogous to aim setbacks on getting hit). Perhaps balanced in a way that the person hit would loose a bit less of the distance as the one shooting looses while taking one shot with equal abilities and a lot of small hits being more effective on slowing than one big hit. Meaning stuff like: 1) tank would be able to get personal with an archer in the end and smash face (Not really with 2 archers of the same level. And the reverse with 2 tanks chasing 1 archer) 2) Archers would get a mobility advantage, but get fucked if caught (Higher level archers could go Lars Andersen on a bunch of fighters).
Aiming:
Lots of hearthlings mention getting rooted while aiming. It sucks. So does the angle restriction. One could argue those are the biggest problems. Some even say to get rid of the charging/aiming mechanism at all. I hope there is a way to keep it. Also instant arrows would really suck for melee people.
First of all - you can aim while moving with ctrl+left click. It does however rapidly decrease the aim bar dependent on distance traveled (as far as I gather). As a result with high MS I can keep the aim bar at half while Walking. And Crawling is useless (unless tanks would be slower (but I'm still not going there) or you can slow-spam enemies). Add to that Run and Sprint are disabled while aiming. Since the aim decrease is based on distance (as I gather), horse aiming on the move is impossible. Also you can't shift+ctrl+left click to move continuously. Also, drawing an arrow interrupts movement. So does shooting if you're moving while aiming.
I'd suggest: 1) Re-balancing the movement aim decrease so it's not as aggressive. Maybe even make it half-viable while running for higher levels. 2) Enabling running and sprinting since PvP is a running fest anyway (maybe a credo bonus? hunter credo will need a new 5th bonus after fixing animal quality sc ;p ) 3) Make aim decrease on a horse the same as on foot in the relative speeds. 4) Add shift movement and get rid of movement interruption.
Second - with how aiming works it makes the archer very clumsy and with a mobile target you're never sure if by shifting your aim you'll be within the angle or instead of hitting the target you'll set the aim-bar back, which could be bad in PvP. Instead - make the aiming angle line follow the mouse, but angle change decrease aim bar. Balance it in such a way that you'd only lose like 1/4 aim bar in a 30° declination, but would loose all of it in a 180° turn. Also seeing a shrinking accuracy cone would be much cooler than an aim bar, but mr. jorb said reasonable.
This would also mean that to loose all aim to click to move backwards from the aiming direction since the aim line (cone pls) would follow the cursor. Or not if you're already moving away and movement interruption is "fixed". Not sure of the implications.
In melee you just pick a target and your tune will auto-run towards it. Removing movement obstacles like this and putting archer mobility at least on similar level with melee would be a good start.
Range:
The max range is disappointing. No way to draw an arrow before your face gets smashed in. I'd suggest expanding the range, yet making the accuracy cone larger. With high enough MS you practically never miss even at max range.
Damage:
Not sure if it's the major thing that makes it irrelevant. Should be easy to balance anyway. Right?
Crossbows:
Get rid of or make the charging/aiming really fast (since an x-bow doesn't require drawing). However add a reloading timer. This would add another interesting tool in an archers toolbox.
Shields:
Just wanted to add that I absolutely love RedSkies idea.
Sorry for the text wall . tldr: read the bold parts. Probably missed something and ready to adjust my thoughts. Cheers.

E: Forgot to mention the tower topic. Would be a dream come through to have guard towers and outposts like in AoEII (not to say that H&H tower is fugly) and larger palisades with platforms for to stand on with an increased range and arrow block chance buff. Sounds like something really prone to PvE abuse, but not much worse than exploits like boat hunting.
btw love the game. How devs listen to the community is just inspiring.