Controversial article from the BBC I must admit I agree with this bit: http://www.bbc.co.uk/sport/0/football/23680545
That's what seeding is, in whichever sport it is applied. It is designed to make it more likely that the closing stages of the competition involve the best teams (or in the case of e.g. tennis, the best players) in the competition. Typical of the BBC trying to pretend there is an issue when there manifestly isn't. As the article acknowledges, the current system has the approval of the European Clubs Association which includes the vast majority of clubs involved in both the CL and Europa League.
Seeding is crap in general. For me the joy of cup competitions is the random nature of the draw. If Real Madrid draw Barcelona in the first round, so be it, it's what makes you "champions"