It's not that bad, but Apps are only put to sleep and not closed if you go to another one. They would have to implement another solution for that so that you can really close them to free up RAM.
But a nice sideeffect: Firefox uses less RAM.
Isn't this the normal way you use RAM now a days? It is put into Available RAM, where it will get removed the instant you don't have any free RAM any more. Basically just a way to improve loading times without any impact on the end user.
Say you have 6 GB RAM, not that rare now a days. Running your average Windows 7 session takes somewhere around 1.3 GB of RAM (chat programs, browser, pirating programs). This means you have 4.7 GB free RAM, yet Windows will never show that since it caches things to make them load faster. As I understand your comment 8 takes it a step further and doesn't close programs until the RAM is needed for something else.