Wlakiz have you played and raided in other MMOs? Just because the final boss is very hard doesn't mean the whole next tier of raiding will be. It is common that the final boss is much harder then the rest of the instance, and they can give us bosses that could take a week or two with another final boss that takes a month or so and I am sure most raiders will be happy. Heck turn 4 was easier then turn 2 IMO, but every guild is different, and some people find some things easier then others.
So turn 6 doesn't have to be harder then turn 5 to fit into the flow of boss fights that most raiders are use to dealing with. The main issue I think you are referring to is that people in all 90 gear will most likely destroy CT, and some feel no need to even do it. I like to raid to fight different bosses, so even if it is easy, I might have fun doing it, but not everyone feels this way.