The main reason all of those champs are ban is simple, they dominate early game, and at low elo's people feed them early game and once they are fed, there is no "falling off" or coming back. You will lose every team fight.

*Note this low Elo*

shaco - early ganks, people forget to play passively and get taken out early, gets fed, destroys everyone

Morgana - High burst damage, with great sustain, mid gets caught with a snare + aoe + ult, easy kills, will destroy your team in a team fight

Shen - He is shen. High damage, high survivability, great initiations, Dat ult, and the taunt + jungler gank is nasty.

Kassadin - I've seen nearly every at low elo's who has gone mid, die to him, and then he 2 shots your entire team

WW - Gets a kill here and there, and suddenly begins to snowball due to players not understanding how to deal with a WW, either in lane or ganks.

Rammus - Ad carry is mad scared of him. (although i don't tend to see that many rammus bans)

Just my opinion as why each are banned, and i agree with these bans at low elo, except i'd swap rammus for olaf or shyvanna, i hate them so much lol.

I agree one hundred percent. if i have ban priveledge I usually make 2 bans to help me not get counter picked top or mid and shen is usually one of those and the third I "ask the audience" which is usually morgana,WW,Lee sin.

I cant stand anything more than a shaco ban. Shaco is so useless with a couple wards and smart map awareness. Rammus since his debuffs is useless early game and once again wards save lives.

Shaco rammus and kass bans are rage bans because if theydont get banned someone stomps them cause they pick horrible champs to lane against them.

Really?
For me the bans I see most are
1) Morgana
2)Kennen
3)Mundo
4)Shen (not sure why... hes fairly simple to beat)
5) Lee Sin
6) Udyr

Amumu bans have fallen off thanks to the Shen buffs. Jungle Amumu can be played in ranked again ^_^

- Mageinta Warrior

kassadin sucks until lvl 6 and in a solo lane a lot can happen to change the course of his game before then

I ban Kassadin to keep my teammates from picking him.