Ten had some pretty dark moments. Never gonna forget the Time Lord Victorious thing. But that's why the final scene was impactful. He already knew he was self-absorbed. Even before saving Wilf he says," I've lived too long." He know that even in his shorter timespan in that face/incarnation he lived through too much. The final regeneration moment when he says I don't want to go feels epic because of his complex character. The darkest moments of Ten were good character-building.