Well, of course changes to character design and such would require some re-coding of different aspects of the game, so does every expansion and major update. Better server hardware facilitates that exercise, and that is the point. If you no longer have such tight budgets in character data because you can double the database bandwidth for writing back character data, or loading characters into active zones, or whatever other aspect you want to discuss; you can start expanding on the existing character data without running into limits defined by the older hardware. Of course there will still be limits because clients need to be sent some character data in order to display other characters.
But let's not pretend that improving the server side would not benefit the game, which appears to be your position. I'm sure they use storage arrays, and there will be any number of in-line caches in the components of the system, but increasing the system bandwidth, number of processors, network bandwidth, system memory and so forth all have impacts in terms of what the server can do within a specific period of time, and alters the calculation as to how much character data can be moved/processed. That has a direct impact on what changes can be handled with respect to characters.
Honestly, the way you are talking, it sounds like you are basically saying that improved infrastructure means little to nothing - in which case perhaps we should all stick to PS3s and laptops with DSL network connections and be happy about it?
