George R R Martin is basically a sadist. He invents a compelling, interesting, and genuinely 'good' character who has noble motives, and kills him later in the same book.
He's so intent on breaking convention, that I feel like it will become predictable when he kills characters later in the series.
It seems that way.
The death of Ned Stark was brilliant and served a purpose. And it let people know that the show would continue to be totally unpredictable and break the conventions.
And even the deaths of Robb and Catelyn seemed 'right'. They had a long run and it was done beautifully.
But to me killing off Oberyn at this early stage is just overdoing the whole 'breaking the conventions' approach as you said. Martin is basically just being a dick, here.
He was a brilliant and charismatic character with endless possibilities as a good and honourable protagonist to sort of pick up where Robb left off in a sense as the chief opposition to Tywin.
And to me if Tyrion lives then his death serves no purpose. It's just a waste of perhaps one of the top two or three characters in the shows history.
As a viewer it almost feels like Martin is taking the piss. Just trolling his readers/viewers. No surprise that from all reports book 4 sucked. Maybe it would have been better had he not killed Oberyn off!
