I'd rather see some other things happen first.
Insanely hard systems and mini-games that a casual/average player could work for years, and never get any kind of decent reward, need to be revisited. Casual and even hardcore players give up on enjoying those aspects of the game when they realize that it's virtually impossible to receive the reward through regular gameplay.
Skills that are extremely tedious, boring, or very slow to gain need to be looked at, too. There is nothing worse than trying to immerse yourself in your character's development when the only way to progress your abilities is some mind-numbing, repetetive task that does nothing to enhance your experience and might not even fit with the environment very well. Skills that could be gained from both active training and passive experience could help bring back more adventuring and fun at all levels. Of course, there will always be some skills that just aren't very interesting to master, at least in the way of adventuring. Why not add in some Quests of appropriate difficulty as an additional avenue of Skill Gain? It would certainly add some variety, and might even help break those frustrating "walls" we have all hit at one time or another.
Community Collections... I see lots of requests to improve these. Expand the items that are accepted, revisit point values and reward costs to see if these are balanced when compared to the amount of work/time involved. I think we all would mind those 'useless' loot items much less if they were no longer 'useless'! Make them worth points towards a Community Collection or Spring Cleaning type of Event, and have these things active permanently. Switch up the rewards perodically if need be, but make sure players have a reasonable amount of time to get them first. Let players know well in advance if rewards are due to be cycled out soon.
I brought these points up specifically for a reason. I would love to see Mythic get a handle on cheating - have it be easily detectable, quickly identified, and consistently punished - but at the same time, I would also love to see players have fewer reasons to even think about cheating or simply buying their way through the game. Making character development and skill gain fun again would go along way towards that...why beat a golem while unattended when you could go out and *play the game* with others, having fun and making friends along the way. Bring back adventure, excitement, and creativity to our character's journies to Grandmaster and beyond, regardless of playstyle.
Making collection rewards and other systems' rewards more attainable not only discourages UMing and Scripting, but also Duping of the more desirable rewards. Not to mention it could make all loot worth *something*, and even renew interest in once-popular skills like Fishing and Treasure Hunting. All players could participate, regardless of skill, by gathering common things while playing the game.
Players cheat because there appears to be little risk involved, and high reward...in some cases, rewards that are almost unattainable any other way.