This topic has been brought up an innumerable amount of times, and I laugh every time that people zero in so hard on the ilvl cheese component of it.
CT has so many bias's towards it that fixing ilvl cheese would change it from being 80-90% of your roulette choices to 75-85% of your roulette choices.
-CT is the only raid required by MSQ.
-CT is the only raid that is mandatory to unlock, meaning someone can easily ignore every other alliance raid if they choose to do so.
-if even one person queueing is < level 60 on their job, all 23 of the other player's individual progressions and choices are irrelevant. You could have had all 23 of those other players be Tower at Paradgim's Breach compatible but that one dude at 58 instantly drags them all to CT. The same thing occurs if someone is <70 but they never unlocked the void series, or <80 but they never unlocked Ivalice, etc. Seriously, next time you get into CT go analyze everyone else in the alliance. A not insignificant portion of the time, you'll find someone <60.
-if it is one of their options in their wonderous tails book, a person hard queueing it will automatically drag everyone to CT.
-CT is the only raid series that grants light for ARR relics, so someone may be inclined to cheese for that purpose instead so they can double dip.
-The Allagan Catalyst item that drops in the CT raids has a very wide range of uses from being useful for crystal sand acquisition in the HW relic, to crafting the replica high allagan glamours, etc.
-The SHB relic has an option for 15x CT runs for one of its steps.
ilvl cheese is literally a drop in the bucket for the CT bias. Seriously, anytime I see someone blatantly ilvl cheesing, 90% of the time in the run, there's a new player message or someone's <60 making the ilvl cheese irrelevant. Nullifying it will be practically indiscernible as far as how much CT you get. Alternative solutions also don't really work like making CT harder since:
a) Yoshi-P has said in the past he wants large scale content to be carryable by the smaller subset of better players in each group, meaning they'll never do anything to make CT harder in the first place.
b) Making them harder will simply disincentivize people from running the roulette, or fishing for the next easiest like Rabanastre or Void Ark, and simply leaving if they get anything but them. If someone isn't interested in doing the harder raids, they won't do them. They'll take the 30min penalty and move on.
The "best" solution is to move CT to its own roulette (it cant move to MSQ since the roulettes are coded in such a way that prevent duties of different party sizes from being mixed together. this is the reason why ifrit/garuda/titan normal are in leveling and not trials, despite every other 'leveling' trial being in trial roulette instead) and just give it the same rewards as current alliance roulette. Anyone who wants their easy CT run can go in and get out, and only those who care about doing the other raids will queue for the current alliance roulette sans CT.