Irony in Richard's Speech and Ability as a King

It is very interesting to me why Richard II acts as such a weak, inconsistent king, yet he speaks poetically and beautifully, delivering (arguably) some of the plays most eloquent speeches. He frequently cites anecdotal analogies and using other metaphors and symbols that are made because of his extensive knowledge of history and mythology. I'm aware that articulate speech and being a good king are different, but I think there's a definite reason as to why Shakespeare would implant such an odd irony in the play's central character.

His most recent, captivating speech occurs at the end of Act III scene ii, where he is expressing his feelings of death to Aumerle. It states, "For God's sake, let us sit upon the ground,/ And tell sad stories of the death of kings -/ How some have been deposed, some slain in war,/ Some haunted by the ghosts they have disposed,/ Some poisoned by their wives, some sleeping killed,/ All murdered" (ln. 151-156). His sorrow is articulated very poetically, and it makes me wonder why he makes some horrible decisions yet can recollect on his mistakes in a profound way.

Perhaps is it simply to show what truly makes a good person and a good king. Simple articulation doesn't equate to good kingship. It could also be a critique on kings by Shakespeare, the opinion that politicians and kings speak poetically to create a facade; under all these flowery language lies dimwitted decision making and ill-favored fortunes. I'm assuming that this trend continues through the end of the play, and the two concluding acts may serve as more evidence for this particular aspect of the play.