Some things I have against this system:
Promotes kill stealing to gain more ELO. (which also promotes "HEY IM GONNA CHASE SO I CAN GET THAT EXTRA ELO WHILE THE REST OF MY TEAM DIES")
If you're doing bad, you can just d/c and lose 14 instead of 17 ELO.
Bottom lane is reliant on ADC and support. If one feeds giving the other side an advantage, that means both will end up with bad scores.
One lane can snowball (or even jungle) and completely screw over all other lanes resulting in bad scores for them too.
By putting a negative for surrendering, you make it so that people would rather either AFK (so pretty much just wasting their time) with the risk that they would die if they consistently lose team fights while still trying if the other team is too far ahead they will start losing more and more elo instead of cutting their losses and moving on to the next game.
If one person wins lane, but all other lanes lose and that person end up constantly dies in team fights, isn't it unfair to them that the the others couldn't pull their weight if they end up dying a lot to fed team tower diving.
Promotes winning teams to stay and farm the other team instead of killing nexus in order to maximize elo gain.
Kills aren't everything. You can get kills but still be behind in gold if you can't CS.
Assist gains still don't fix the problem of (Hey that guy gets kills and gains more ELO than me, so I should play something other than support so I can get ELO faster)
Jungle affects ALL lanes. If your jungle is terrible, but their jungle is good, gets kills, constantly harasses your lane, and tower dives, you're screwed. (aka Hi, I snowballed off a bad lane, so now I'm going to destroy your lane and constantly harass you because you're winning. Have fun losing elo because I got fed by your teammates)
Oh and "Hey I lost game before laning phase even ended because it was 20-5 by 13 minutes because of all the trolls I have. I did okay in my lane and went 3-3-0 but I should be punished and lose ELO because I have the same deaths as kills"
As to winning teams wanting to farm, they can only farm so much before it is capped, and even with out this system i have seen team who will avoid killing the nexus and just sit at the fountain with a blitz farming anyways. I would also like to explain that a good player will be able to gauge how strong the other player is and if they should haul butt back to base to buy wards so they can farm with out it going from 1v1 to 5v1 etc. or if they should be safe because their team is doing their job and calling MIAs regardless of how poorly they are doing. It isn't the junglers job to ward for you.
As you put to view, jungle is a major roll! so if they do their job, why shouldn't they be rewarded? If they harass and do it well. Good job, here is a couple extra ELO. If they are doing badly, no ELO for you! With this system it will also force the jungler to be in lane instead of just staying in the jungle. (example: an olaf i was in a game with never ganked once and left the jungle 3 times simply to cover lane and he was 0-4-1 at the end of the game with 140 CS) I am trying to stop these people, or at least punish them, from not doing their job.
To surrendering i say, You never know how late game will end. I went for 56 minutes as akali with an AFK mundo on our team the other team had 60 kills we had 30. We didn't surrender, fought tooth and nail, kick and struggled and won with 4 people in a loosing game. Mostly its because the other team got cocky and thought they could just steam roll through us, but we took out their carries like a good team will. With my system i would have gained ELO for not surrendering and never giving up. so i will try to implement a system for AFKs so that it doesn't seem more appealing to AFK rather than surrender.
Thank you for the feed back!