Simplicity, Complexity, and Price and then the law of Diminishing Returns. I own the one box Lamm L1 preamp and the four box Lamm LL1 preamp. I have listened extensively to both in my system over the last year or so. The former is simple and inexpensive if you can find one. The latter is more complex being a dual mono design with separate power supplies in a four box attempt at the SOTA. It is also much more expensive.
Both preamps sound great and I would not know what I was missing if I did not directly compare them to each other in the same system. But, if the system is resolving enough, one can hear the differences and perhaps appreciate the improvements brought by the more complex and expensive LL1. The noise floor is much lower and one hears more of the information on the recording. The LL1 is just a degree or two more natural sounding because more information is resolved and presented to the listener. Live music has an incredible amount of information and the more that can be captured during the recording process and then played back through a system in a listening room with minimal corruption, the closer the presentation is to what one hears live.
It is the same with the Micro Seiki SX8000II, the American Sound AS1000, the AS2000, and the Absolute Nothing turntables. They all have the same DNA and sound different as a group from other turntables I have heard, but each step is a bit more natural sounding. The returns do diminish, but they can certainly be appreciated. We listen to the options available, and we make our choices.