It takes a lot more writing and figuring out what you want to write with assembly language than with C++. The purpose of the higher level languages is to allow you to think more in human terms, more abstractly, rather than working with registers and memory addresses directly. I can write things with C++ in hours that would take me a solid week, at least, to figure out how to do with assembly language. And my C++ compiler checks my spelling of functions before generating the machine language for me, so it's a lot harder to make a mistake, and easier to track down the ones I do make.
I use assembly language when I want to optimize something that takes a lot of processing time and the compiler just isn't making it as fast as I want. Other than that, I use higher level languages for the majority of the programming I do.
Lee