Where to begin:
A great idea would be to stop revamping old zones in favor of brand new ones. What this does currently is keeping the same amount of zones in the game. I see no problem with 'updating' the current zones, maybe added a room or two and just cleaning up the general descriptions and what not, but having someone devote their time and effort into a zone that's already been in the game just seems like a giant waste of time.
Arena has been asked for for nearly a decade and I'm glad that something is being done about it.
Removing legendary would be a great change of pace. Instead of grinding these dumb skills that you're never going to use and grinding an absurd amount of rank mobs for a measly few % only to go on and legend and mostly likely stop playing shortly after because there is no more incentive.....my idea is to remove legendary and increase the amount of ranks that are available. You could include the current legendary ranks within the system already (slightly nerfed) and add a few other fun/utility flags in there for purchase. In order to make this successful, the current ranking system would need a major overhaul. There's absolutely NO reason that running a zone shortly after someone else gives you astronomically lower rank % than the first group who ran it. What this would also do is make repopping gear seem not so bapting awful. There's absolutely no way I want to run some shitty zone AGAIN after we just ran it for the POSSIBILITY of my item loading and coming out with 30-45 minutes of my time gone and absolutely zero gained from it. With this type of system, the rank cap should be raised to 100-150. Make the ranks cost more points but increase the gain per mob. Another downside to this is having to adjust the smaller, weaker rank mobs to not be spammed. I have no idea why every single mob in Thanes Mansion west of Solace is a rank mob, but to avoid abusing that, those ranks were have to be set far lower than others.
I would love to see rangers put back into the game or at least take a look at sky scouts. The ranger class was an awesome mix of utility and damage. Tracking, hiding, sneaking, casting refresh, small combat buffs, bash mode vs bow mode, parrying, rescuing, it was a great mix and you could play a handful of different ways in each zone. I don't see anywhere in any of the dozens of Dragonlance books Iv'e read mention anything about 'mountain, ocean and sky scouts'. Dude, get real. I'm fully aware of magic and casters and this game is fantasy, but if you want the 'immersion' feel, get rid of bapting aquaman and stupid ass IRL grizzly adams. That RUINS the immersion feel. I like the idea of different 'paths' for classes, just ones that make sense. Marksman path for bow oriented rangers, Hunter for bashing/hiding/sneaking/tracking and possibly a little buff to allow them to tank. Shield/Parrying combo where missing a bash doesn't floor you so you can still provide utility while not taking tons of dmg.
I don't necessary agree with 'unlimited' gear, I do feel like some items should become unlimited. Make these items like + damage come with some negatives, something to use UNTIL you find a limited piece to replace it with.
Sets: I think the class sets should work like this. Instead of having set mobs have an OK % to load, I think that any mob that is higher level (25+) should have a small % of loading a set piece. This gives them a random feel and would mix things up a bit. Instead of spamming Sarson over and over for a random, non locateable piece of gear, you could make it a point to go out and hunt big mages with the hopes of finding one of the pieces. This game has far too few 'random' elements to it. Having a little bonus for just going out and zoning and doing shit should be a nice treat.
I could probably make 10 more of these posts and I will continue to add on when I think of new things. These are just my opinions and views from someone who has spent FAR too much time on this game that any adult should.