Windows keeps improving the memory manager.
The idea is to keep as much needed data in active system memory while also keeping enough free so you can load a new program, like a game, without being forced to unload data.
*So using LESS memory isn't necessarily better.
In my experience, and from my reading, memory management seems to get better with every version though again it's hard to compare directly simply based on memory usage.
The actual GAME usage will be identical (game itself, not total), so unless you are running out of memory (it will warn you) there is nothing to worry about. In general 8GB is plenty unless you have a web browser open using a lot of memory as well as running a demanding game or some similar issue (Windows may still swap the browser data to the system drive).
Windows can generally use LESS than 1GB of system memory if it needs to (besides the game), so even if you used 6GB out of 8GB when starting a game it can probably free up 5GB or so if it needed to.
*Windows will also look at the total amount when deciding what to buffer. My dad's laptop now has Windows 10, but because he only has 2GB it uses 1GB only after startup.