I realize many of these are already stated above, I believe Square is probably tallying "votes" and these the ones I see are the most useful.
Suggestion: Bind should not force the mob to attack anyone not already on his hate list.
Suggestion: If any member of a party/alliance are already on the mob's hate list, someone outside of the party/alliance cannot claim the mob before it is 100% health. This should go for any yellow mob that has been affected by my party/alliance.
Reason: I have been MPK'd with Dia on MysticMaker Profblix because I had just dealt with an add, and a non partied RDM Dia'd Mystic. This interrupted my casting of Fire III (You cannot attack this target, it is already claimed), Mystic then promptly killed me, and my duo partner, with less than 5% of his health left. We were unable to do anything but try and cure ourselves, but we were low on health/mp, so we died. In addition, it's not fair for someone to get an easy kill by MPKing a tough NM, or an HNM when the original group died to it. Make the mob stay unclaimable unless it's at 100%, on EVERY NM/HNM.
Suggestion: If you rework Leave, I would do so like this: Non~Aggro pets that are given Leave will act as they do now, and in addition will not link to anything on their way back to their original starting point. Aggro pets will not link or aggro, but also cannot be recharmed if they return to 100% health prior to returning to their starting point. This will discourage folks from randomly leaving aggressive pets far from their original starting point.
Suggestion: GM's need to respond publicly to MPK offenses, and make it known that players were punished for MPK, and the extent of the punishment.
Suggestion: GMs need tools to be able to "play back" the events so they can see the absolutely obvious MPK at many of the NM/HNM/Triggers. Allow a GM to be able to view recorded "footage" of mob and player movement, Requested spells/job ability (to see claim spamming tecniques), magic/abilities used during that time, along with text typed by those in the zone, during set time frames. Have your servers record all of the time during the obvious time frames, such as when a God Trigger is used, during the spawn window of NM/HNM, etc.
Suggestion: Make god Triggers Rare/Ex. This will stop a lot of griefing. Our LS had a party getting XP in sky yesterday, Ulli popped, and they claimed, but they were promptly MPK'd by a gil selling operation. Absolutely unacceptable junk for a game that is for our enjoyment.
Suggestion: Continue to Offer more level appropriate BC style battles, even if you come up with new (farmable, rare/ex) triggers besides KS and BS that allow comparable rare/ex gear and can be accomplished by individuals and/or small groups (3, or 6, capped and level appropriate for the gear). If you offer rare/ex alternatives to some of the highly sought after equipment, and do so in BC's that are immune to MPK, you'll offer the player base an alternative location to attempt to retrieve gear that they desire.
Suggestion: Offer single instance (BC style) battles when triggered NMs are used. Basically make triggers create a generated item which can be traded to all participants. "Warp" everyone holding a generated item, ala the Timeless Hourglass/Perpetual Hourglass into an instance of the entire zone when the trigger is used. Noone else will be in that triggered zone. The zone has X hours of life, and closes automatically when the triggered whatever is killed, or if the time limit runs out.
Suggestion: As a side note, and on a similar tangent, modify the drop rates of the new rare/ex NM drops. Killing the same level 14 mob 13 times with no drop is getting annoying. The drop rate appears comparitively much worse than it was before they were made Rare/Ex. If it's the same, state so to the community, and consider increasing it.