You may be thinking that using RAM as a cache is great, but you don’t want these program files and other data taking up your RAM. You’d rather have empty RAM available so that programs will launch instantly and the memory will be used for what you think is best, not what your operating system and programs think is best.
However, this isn’t a concern at all. Whether your RAM is full of cached files or completely empty, it’s all available for programs that really need it. Cached data in your RAM is marked as low-priority, and it’s instantly discarded as soon as the memory is needed for something else.
Because this data can be instantly discarded when necessary, there’s no disadvantage to using the RAM for cache. (The one potential disadvantage is users who don’t understand what’s going on becoming confused.)
Empty RAM is useless. It’s not any faster for the computer to write data to empty RAM, nor does empty RAM use less power. In fact, assuming you’re launching a program that may already be present in your RAM’s file cache, programs will load much faster when your RAM is used rather than when it’s empty.