My suggestions (for what it's worth)
1. Collision Detection - It would be a nice touch to give a more life like feel rather than having some other character running straight through you.
2. Character creation - Though it has been posted on here before, it's very true. Most "mmo's" really seem to limit to what you're able to do to customize your character, another thing that could make this different would be to add more changes as you progress through the game. Example (based on a leveling system we'll say) You're level 1 and you setup how you like it and create and play. a few weeks later you might not like it anymore and decide to never take your helmet off because you now realize your character looks like something you have nightmares about when you sleep at night. Lets say you're now level 10, well you then have the ability to remodel your character into something different, whether it be something mild like a different hair style, maybe add some scars or possible tattoo's? To something major like a face change, possible bigger bulk in your character size, or smaller frame depending on what fits your style best. The possibilities would seem almost endless. I can't say how many times I've made a character, got to end game and decided how much I dislike the way the creation looks that I did or how much they have not changed even though I've been shot by thousands of arrows or slashed by a thousand swords haha. Just ask my wife about this one, she could sit down for hours just making people over and over.
3. User interface - Games lately seem to try to go over the top with their UI's (User interface) The fact is, a simple interface is all you ever need, i don't need sparkles and flames flashing in my eyes when something is ready to use or when I do use it. I also believe it would help on visual lag and other possible bugs from which i have seen in other games (no names mentioned)
3. Inventory - I love the thought of it being based on a weight system and not a limitation of how big of a bag you have and how you can try and manipulate it's shape to fit properly inside the bag to make more room....at that point i feel like I'm playing a bad version of Tetris lol.
4. BIG NUMBERS! - I really enjoy running up to something and hitting it for thousands compared to hundreds. Small number games don't seem to satisfy my thirst for blood when fighting an opposing player or NPC haha.
5. Repetitive motion - I think it would be a great change to have skills or spells have different motions. Example, a caster class, now lets say he just wants to spam a fire spell, lets say "Fireball." It'd be a neat change to see a caster cast his spell by charging it with a closed fist and casting and say the next fireball he slowly brings his arm behind him with an open fist and throws it when ready, some type of combo system or random skill graphic would be nice rather than seeing the same thing 5,000 times per level. The same idea could be implemented with say a melee class or healers and so on.
6. Rag doll - I think rag doll would be a great thing for an mmo to have, I would love to see the body of some one just crumble to the ground unless there was a good looking animation of some one falling to the knees and then flat on their face haha.
7. Player level equalization - It seems like this has not been done all that much in a lot of games that I have seen. The ability to match levels with lower level characters AKA friends. Some times it seems that your friends new or old, main or alt characters can't enjoy grouping up on things together because of the lack of experience or drop rates that hinder then from doing so. The ability to match a level with a player and not receive a cut on something for just helping or goofing around with people would be a nice thing. Of course you would have to take into consideration that a high level character could help rush things on a low level character would seem to unbalance game play, if there were a way for say a level 20 character to match to a level 5 character would be a nice change instead of standing out of a party or scenario and being bored with nothing to do.
8. Gore - Something that seems to lack in mmo's. This games style sure does not look like it's going to be about care bears and rainbows haha. I think it would be nice to see some type of blood rather than a purple splat/haze animation or spark when you hit a character/NPC. Other games with the CryENGINE have had gore effects, why should this one be different? Give us something that makes you different!
Or at least have it an option!
9. Content - A lot of people seem to get upset over content in games, some people have 15 minutes to play as where some days people want to stay home and play games all day (me included on my days off from work haha) It'd be nice to see something more user friendly to fit those people. I know you guys are still in the process of working a lot of things out, these are just my "personal" suggestions though.
10. PvP - Will this game have it? I hope so! There is nothing more I would like to see than a trophy of some one I have beat in PvP impaled on a spike on my shoulder armor whether it be his head or a skull chained to my characters waist!
11. Sound effects - Sound effects are key to almost any game. Go play almost anything right now with the sound turned off and it'll leave you wanting something more. I love the character styles in this game, dark, evil, chains, skulls, CHAOS! Though other games have those things, how come you never hear it when you're running around? I would love to hear a group of characters running in an area and getting the full effect of that armor in sound, being able to hear chains shaking, plate armor clanking on other pieces, weapons being blocked by shields and it not sounding like a trash cans getting hit by a baseball bat. I want to hear the sound of a group of 32 people charging and not just hear my own foot steps, I want my speakers to shake of my desk! haha
It's all just what I would love to see in games now days. I could keep going on for days but you guys already have a ton on your plate to deal with haha!
Best of luck to you guys! I'm really excited to see what you guys can do.