Finding quality raiders is hard nowadays. We've gone through a shaman who didn't use their Ascendance/other CDs properly, and when they did they spammed Lightning Bolt in Ascendance as elemental (they also maxxed out at around 80k DPS in ~510 gear). We had a hunter who had no idea how to AOE as survival... apparently Multishot is a hard concept. Had a mage who barely used his level 90 talents and had no idea what Ice Block was. I can go on and on about other applicants who outright failed miserably. People who have no idea what a hit cap is, etc.
People are just lazy now. You can nerf the content into the ground and they will still probably have problems with it. To be completely honest, if you haven't cleared normal ToT by now then your guild is either happy with it's easy-going pace, your raiders don't care, or your leaders aren't very good and you're using horrible strategy.
Downtime between attempts also plays a factor in casual progression. Depending on the run back, my guild pulls again within 3 minutes generally. Some of the casual raids I've seen sit around and tolerate random AFKs between wipes, often taking a large chunk out of their raid night.
Bottom line is there's a million factors in play when it comes to ToT progression. I think it's silly that casual raiders are calling for nerfs. Work harder, friends. Put some effort in. I'm fairly certain that Blizzard doesn't design raids (outside of LFR) for friends and family guilds who refuse to read up on the content and refuse to discipline their raiders.