There's a saying that has been becoming more true as the years go by:
Processor time (and memory) is cheap
Programmer time is expensive
Apps are more bloated now because of the libraries that make programming easier and more powerful.
Sure, if everything was written in assembly, we'd have smaller, faster applications. Without the libraries though, we would have FAR less applications.
We'd also have a lot less features, because writing a non-trivial application in assembly language is bloody difficult, time consuming, and error prone. It simply isn't practical.
Hardware is cheap. Unless you really need the very fastest software that can be written, use higher level languages to get less errors and faster time to completion.
Even if you DO need something to be fast, most of the time, you can throw more memory at the problem to cater to the application size increase (your DATA is generally far larger these days anyway), and optimise the 10% that accounts for 90% of the CPU time in a lower level language.
Writing 100% of your application in a low level language is a waste for the vast majority of software out there. Also, modern CPUs are so complex, the number of programmers out there who could do a better job than an optimising compiler is becoming fewer by the day.
However, all that aside : people's expectations are changing.
What used to be good enough, in terms of processing throughput, no longer is.
DVD -> Blu-ray. 800x600 screen res -> retina display. 8 bit single channel audio -> 24 bit multi-track audio. 2d bitmapped graphics -> OpenGL. Processing all that extra data is not free.
Even if you were to write in assembly language, system requirements will still go up as people's multimedia expectations rise.
