Oh, sure, it's true that much software is slower than its predecessor. Windows 7 is considerably slower, given the same hardware, than Windows XP
Except that it isn't. A typical machine with 1GB of RAM will perform better on Win7 than on XP, assuming drivers for everything are available. I have old laptops that have received a nice performance boost this way, with RAM at the limit of 1.5GB.
It's obvious why. Win7 benefited from a lot of optimization using tools that simply did not exist when XP was being developed. It manages caches better, deals with multiple DLL versions better, reduced memory in key areas and fixed a lot of little bottlenecks that slowed XP down and made Vista the absolute dog that it was.
Android was the same, upgrading from early 1.x and 2.x versions. I remember when 2.3 came out and my ancient HTC Hero got about twice as fast as before. Massive improvements to the JVM (Dalvik) were responsible for most of it.
Your other points are mostly correct, but the idea that software is always getting slower just isn't true.