I am often asked why the Acrobat application is so large, in fact I get the same question about the Reader application too. I wonder if people think programmers are getting sloppy and aplication software is needlessly large these days. I do recall learning to write assembly language (yes, I'm THAT old) and being told to save every byte.
The simple truth about Acrobat is that it must meet the requirements of very large and disparate user community. Everyone from Architects, Lawyers, Educators, Engineers, Marketeers, Musketeers (nope), Governments, Creatives and individuals, all use Acrobat for differing tasks and jobs.
As a result, when Adobe makes an upgrade, we add a whole lot of functionality improvements. The perception issue we have is that each individual might only notice a small percentage of those in their daily lives, depending on the parts of the product they use. Believe me though, the changes we make and features we add are driven by customer demand.