People who are unhappy are always going to be more visible than people who are happy. And with any product you will find people who are unhappy with it. Even the Nexus One and iPhone can't escape that.

As for why the N900 doesn't have basic phone features, it's because maemo and symbian are two very different operating systems with two different teams (I believe maemo has a very small development team)and two different (originally) design purposes. Maemo was designed to be more of a computer based OS hence it's design reflects that, it's only with the N900 where phone capability outside of VOIP was added. With the N900 the maemo developers likely focused on the computer os aspect of it first and then the phone aspect later.