What more do you want out of a game that is more than a decade old, has over 300+ weapons (possibly even more, very rough number), maps that need no further improvements, a variety of gamemodes added with no further ones to be added, events like Christmas and Halloween that still remain active and updated - take this year's Halloween for example - as well as Valve still keeping an eye on the economy of the game?
Just because they're not updating it at the rate they're updating other games such as Counter-Strike: Global Offensive, it doesn't mean they don't care. They just don't need to step in as much because nearly everything that we need is already here.