There is a lot of support for niche features (3D, etc) pushed into the base reader because it provides a significant business advantage to Adobe.

For example, they stand to benefit tremendously if a government agency decides to go with PDF as their document review format over Autodesk's DWF. The fact that the average consumer already has everything they need to use these solutions is a big bullet point in their favor.

They don't stand to lose much if some picky internet folk (not criticizing - I'm one too) decide to use a free alternative because Acrobat's too heavy.

Why can't they allow you to add in these features if you want these features?

There's no reason why the users should be forced to install all these bloaty features.

Funny you should say that... There are ads plastered al over the DC metro system for nothing but using Adobe PDF to simplify government forms.

At least Apple is up-front that you need Quicktime when installing iTunes, Adobe just installs the kitchen sink...

Umm, they needed more room to put in more backdoors?

Dunno really, I'm still trying to comprehend that myself.

Might be the recommended amount - it probably wants some space for a disk cache.