More rewards, so if they get quite a few MHO's in a week, they should get some kind of reward. The GAG system could be programmed to calculate the average amount of characters used in every opinion and the higher the average, then they receive an Xper bonus.
I would love a badge system that's shown on profiles, when people reach certain milestones, and not easy badges e. g. a badge for each Xper level. Badges for getting Guru or Master status, for posting a high amount of questions that have a lot of interest etc. Basically, badges that newcomers who are here briefly couldn't achieve in a short time. You'd get about 50 Xper for each badge.
I'm not sure what they can do. I don't necessarily agree with the longer answer thing. I rarely leave long answers because I feel like I can get my point across very quickly. Longer doesn't always equate to better. If people want good people to stay then make connections with them, be supportive and then ask good questions yourself.
Perhaps an idea would be to increase Xper points per opinion, question or daily logon while you become a more experienced user. So for example: after the first 1000 XPer points everything stays equal but the points for logging on every day increase by 2. When reaching 5000 points, every opinion will yield 2 points instead of one. When reaching 20000 points, every MH yields you an additional point, etc... That way, long term users staying on GAG would get rewarded.
Less moderation, not allowing question askers to block opinions on their questions, and putting questions that are commented on back into the site feed This site is getting so PG that you can't have debates and shit cause some butthurt anon pussy will block you opinion cause they don't agree with it or cause you proved them wrong. The other day I saw a question titled "GAG do you even lift?" get asked and deleted minutes after it was asked. See, I know that question might sound/be stupid or irrelevant or however you feel about it but damn did it really have to be deleted lol