Now before i get going on this, I would like everyone to know that i haven't played this game in a long time, so I personally haven't gone through a couple of these game killing updates, like the GE and the new wildy. But based on these problems, there could be a solution that could make everyone happy, and no, bringing things back to to pre-GE patch isn't a part of it. Btw, as an avid WoW player, i might implement some of the ideas behind WoW into this.

1.) The Grand Exchange was honestly not too bad of an idea, because now its easier for players to get the items they want in a much faster and less hectic environment, which is an up to it. It's not neccesarily the GE that killed it, but it was this trade limit they enforced upon it. The fact that people can only buy/sell things at a certain price is pretty stupid. Instead of the trade limit, they should make it a market price, where as the value of the item goes up and down based on sales and lack of sales, but at the same time they shouldn't be limited to the street price. This way, the economic geniuses of Runescape will once again have the ability to barter with their customers, (as the more wanted the item is by the customer, the more they will be willing to pay ABOVE market value) and at the same time, selling items worth 1k for 1m (ahem, mage arena books) will still be impossible, unless you're trading with an Rtard.

2.) The arena next to the desert town (forget what its called). Before the stake limit was implemented, i would stake 50k, an amount that, if lost, wouldn't crush me, at the same time that get's my heart racing when i gamble it, to a fellow player, and fight to the death against in one of the worst combat in an MMO (something I'll touch on in a bit). However, now that all i could stake is 7k an amount that, if lost, wouldn't crush me, at the same time THAT MEANS NOTHING TO ME and leaves me filled with boredom. They should make the stake limit within 10k of what the other person stakes, and perhaps the fluctuate can grow as the two stake more. (IE one stake 90k and the other stakes 100k).

3.) Certain skills that meant nothing to most people were ridiculously time and gold consuming to level, like farming, construction, maybe summoning (I wouldn't know). Jagex should implement a more effective, but not neccesarily easier way of earning exp for these skills once you reach higher levels. I'm not sure how, but it would be nice.

4.) Obviously, the wilderness. Solutions to this problem would be too complicated to explain, but what I've come down to is just removing these jokes of PvP worlds and replace them with Pk worlds, where the classic wilderness was back in those worlds exclusively, where as all the items drop as they are supposed to instead of the graves. And take out the damn ditch, that makes things no fun.

5.) A more effective party system would be nice, one that would have a HuD on your party members Hp and other neccesary information.

6.) I personally think i might be speaking out of my arse on this one, but a line of healing magic? Perhaps even a new skill. Maybe? Eh.

7.) This one isn't quite a solution, but just saying, why do 80% of the minigames either really suck or are pointless?

8.) Perhaps i should have mentioned this earlier on the list, but the melee and ranged combat system is a joke! It's ludicrously inconsistent, showing my char hitting 0's at one point, then 30's later. Now, once again, my judgement is slightly clouded because of my personally ideals, but they should add 2 new skills, based on melee and ranged combat expertise, and would gain xp at the rate u would when fighting in "controlled" style of attack (4 xp per 3 damage) and would just be a set of what i will refer to as  "moves" (don't want to get mixed up with skills) that unlock as the skill lvl progressives. Something like specs, only used on a more frequent basis. And also include the minimum damage a weapon could do to an opponent based on the weapon itself, blue splats make me feel nubish.

9.) People are getting those skill capes now, and perhaps there should be more of a reward for having them, especially in combat based skills. And what's the highest skill lvl required to equip somethings, 80? Maybe and expansion to what gear you could have, I'm sure a lot of vets feel they should be wearing different stuffs once they hit combat lvl 126.

10.) Murder every game killing haxor/macro'er/botter on the planet, for cheating in a friggin game to achieve high lvls without playing, which is supposed to be the fun part of it all. Or maybe tell them nicely to stop. That's definitely worked before : /

Edit: I forgot about RWT... don't know how you could prevent without trade limits.