I'm late to this party and I agree with Chad's overall premise, but I'm not convinced that Ubuntu is necessarily the guilty party here. I decided to reacquaint myself with Linux a few years back (initial limited experimentation in 1994 & 1995) by installing Debian 3 (Sarge). I quickly learned that I couldn't get the Kmail app or any PIM application without also installing a full bluetooth stack.

Similarly, I bought a new HP printer for my mother's Mandriva 2008.1(Spring) computer a few years back. Since the printer was too new to be supported by a binary package from Mandriva, I had to install HPLIP from source. I couldn't believe my eyes when a dialogue appeared asking which MTA I wanted to install.

That's right. One of the libraries or other build dependencies for HPLIP had a full MTA (Postfix/Exim4/sendmail) as a sub-dependency!

Shame on me- I never started fresh and loaded each package individually to determine exactly where the bogus dependency came from and report it as a bug. Nevertheless, some lazy package maintainer had simply queried all packages installed on a system and made them all dependencies for that package.