It's not because people wanted it to have a bigger number than the One. It is more along the lines of the One was criticised for using so much resources on non gaming functionality and was looked down upon for only having 5 GB available for games. Now Sony is speculated to potentially block off even MORE ram, all of a sudden the narrative changes that 4.5 is more than enough. There is NO reason a gaming machine should reserve 3.5 GB for the OS, especially when you are putting in expensive GDDR5 RAM. The Xbox One came out the gate for being a general purpose multimedia box, got roasted up and down about how all these resources were being used for everything but the games and Sony came out the gates boasting about being the machine for core gamers... so there is no reason for Sony to reserve as much if not more resources when their claim to fame is a focus on gaming.
Sure developers aren't complaining about the lack of RAM NOW, but 5 to 7 years down the line, the more resources they have at their disposal, the better. No developer will come close to maximizing a system in the first generation, especially when they are transitioning from previous generation's hardware and working within those limitations, but years into development, when they start pushing the system to the max, the more resources you give developers to push the system even further, the better. The less resources used for the OS and the more freed up for developers the better IMO.
