Alright, from what I've seen. Problems: Lobby (New Lobby, shorter waiting time, voting system), Staff (Frequent Mods, more staff, age limit), Players (monthly leaderboards, donor privileges, hacking/spamming etc.).
This is roughly what I've narrowed it down to and I'm going to explain my insight and outlook on each of these things listed.
New Lobby: Agreed, this current lobby has been in place since beta and has only received a small change throughout that time. Give players an opportunity to make a lobby and treat it the same way as you do a community map.
Waiting Time: Should be shortened to about 3 minutes or so to give non-donors a better chance of staying before they get kicked and giving everybody what they came for sooner.
Voting System: A controversial one indeed. The new voting system has not been given a chance to get in it's prime and start truly being effective so players should not judge it so harshly already. Other Ideas, like going back to the old system. Personally I disagree due to the sheer number of maps to play on, the new voting system accounts for that and if anything should at most be extended to 3 choices. Random, a good choice indeed that I personally do not agree with but do not have a problem, I do not want players voices to be left out.
Frequent Mods: Truly agreed, I do not see enough moderators doing what they are supposed to be doing, I understand that they indeed have lives and cannot monitor the servers 24/7 but even the ones in teamspeak that show that they are available yet sit and loaf around (no offense personally to any mods, this does not apply to every single one of you).
More Staff: They are still accepting applications and are strict about it for a good reason, nobody wants an immature and/or unqualified moderator. Good moderators will indeed get their chance to shine.
Age Limit: Now this is something that I really would like to explain to all the younger fellows out there. MCSG does indeed except mods younger than required age if their application is good enough, that is what truly shows how mature or immature you are. Even if you think you are mod material, a 12 year old that is as mature as a 17 year old, you people who say this know who you are, is still a 12 year old. You need to accept this fact, you will just never be as wise, experienced, or level-headed except for some shining individuals here and there. I do not want any of your hopes and dreams of being a moderator crushed by any means and am truly sorry if I have done so but there is a certain line, a thin line. If you have passed this line then you are worthy, if not, you will eventually learn as you grow older and keep playing!
Monthly Leaderboards: Agree with this 100%, anybody new will never get a chance to get to the top 100 even if the leaderboards just keep going and going, newer players need to try harder than veterans out there which should be the other way around in fact. The universal leader board should still be kept, no sense in making people who have already tried hard do so again. Even players on the top of the leaderboards, if they ever so happen to take a break not 2 weeks long they will probably be beaten by other players because they are not dedicating their time to this game.
Donor Privileges: Donors keep the server running and should not be faulted for doing so, the point is, MCSG is trying to encourage players to donate and help the servers to fix any bugs or problems mentioned by many other well spoken opinionated people. If non-paying tributes are, in a sense, given more than the people that pay (such as the donor limit thing) than what is the point in paying and helping the server. Being able to join and kick or voting multiple times is an incentive to encourage, do not fault MCSG for doing this.
Spamming/Hacking: This almost ties in with the frequent moderator thing mentioned above. Mods should keep a look out and frequent the servers even if its just the lobbies to watch for these people. A plug in wouldn't be bad either but let's not have an automated plug in do the job of a logical Mod. Spam should be condensed, I am familiar with a few mods out there, so that if someone were to say the same exact statement more than once it would keep multiplying in one singular #. A little hard to explain but the basic idea is spam and it wont flood the chat, it would be condensed.
Thank you for taking the time to read an enormously long post like this. Have a good day!