Why's Wiki so wrong?

Don't use Wikipedia. A phrase used commonly throughout my education, but why? Wikipedia has become something of a bogey word in terms of education, it was always drilled into us how unreliable a source it is and how we shouldn't use it as a reference. To me nothing is ever going to be a hundred percent accurate or reliable, take newspapers. Half of what we read everyday is not actually true, yet the majority of us will still go out daily and buy a newspaper. So what's different with us using wikipedia?
In my opinion Wikipedia isn't actually a site I would use for information, purely because of how easy it is for anybody to add information to a page. When I realise this, I ask myself why I don't add any information myself if it's that easy? Then I decided to ask some others if they had ever added or edited any wikipedia pages... the answer was no. Obviously there is no technical issue here, as we all have the technical ability to do it if we wanted. My thought, for myself anyway, is that I have been brought up to think of Wikipedia as a site not to be trusted. Therfore why would I want to add any valuable information to it, only for it not to be taken seriously.
During my research into wikipedia I actually looked at the website in depth, something i've never actually done. Doing this, I realised i've never actually read a whole wikipedia page. Usually I look specifially for a piece of information, name or date and thats as far as it goes.
But Wikipedia actually offers you a great deal more than that. It is so easy to look back to when it was created, every change that has been made to the page with a date and name, so maybe we should give it slightly more credit than we do.