User blog comment:Freyamerlin/I want a Season 6/@comment-5763053-20130116111247/@comment-5102537-20130116114550

The explanation seems to be a simple one: they wanted to make the show "more mature" which obviously means that in the "world of adults", happy endings are childish. ;-)

It's a shame. Surprising the viewers by shocking them is a common stylistic device nowadays. Here on "Merlin", it totally failed. They could as well have thrown a meteor on earth that destroyed half of the planet in the finale, it would have had the same pointless but shocking effect. Destruction, misery and death are often used to make a show "more mature".