The whole point of fans getting bigger is so they can push the same volume of air at lower noise than the smaller counterparts.
The 80mm fans push the same air as the 120mm models for the most part for the normal fans, but at higher noise levels.
A 25cm fan should be totally silent, not noisey and not able to be changed by the end user.
160mm fans are the largest I can see becomming the norm, but 120mm seem to offer good noise levels and acceptable CFM so there is currently no need to go up again, especially as thermal tolerances on the hardware are going up all the time, and the components are running cooler.
It is a gimmic in my eyes to sell cases, if it was required then every high end case would have it, the prime example I am thinking of is *** Stacker 830 and the Ss TJ07, top of class for all out cooling and look at the fan load out. All user configurable so able to match the cooling / noise ratio you want roughly.
If it was a ATX accepted component and a standard throughout PC's then it would be handy, but with cheap models cropping up all the time, you just can't guarantee the reliability and if the fan will perform how you want. Also they are usually stuck on gaming cases so enough said about that.
The Thermaltake offering may be the best one at the moment; I just do not see the need for these other than it being the trend. I would mod a 320mm fan in running silent if I needed the performance, but I dont and 10cfm see's me through.