I think most people who use debian would tend to install things using debian packages, which in this case usually means adding cloudera to your apt sources list and using apt-get.
I think the complaint was that it's difficult figuring out how to build Hadoop from source. That page you linked is how to install pre-built binaries, which you rightly point out is fairly trivial.
Sure, I agree that debian people would want to install debian packages.
What debian users/hackers/amateur admins like me really want is packages that are first class citizens, that the debian guys have picked up, sanitised, analysed and made part of the system.
I'll take software from the debian repos every time if I can. And it's pretty damning if people who are familiar with build systems and package creation can't figure it out!
It is a pretty straightforward process:
http://www.cloudera.com/content/cloudera/en/documentation/cd...