1) Ultimately we pray because the king commanded us in this specific service.
2) To say that Hashem would find something annoying is ascribing human emotion and limitation to Him. The Torah can describe Hashem in those terms; we cannot.
3) "Much better for the king" -- Hashem is not lacking in any way, and thus does not need our tefillos or our mitzvos; He has commanded us to pray for our own benefit entirely. See Sefer HaChinuch 433 for some ideas on the topic.
4) "I don't see a reason to pray" -- and in true Western spirit I am the ultimate arbiter of what is right and wrong.
5) "we could spend the extra time" -- Time that has been given to you by Hashem to pray can hardly be considered "extra".
5) "Instead of praying we could spend the extra time doing things like Kivod Av Veam and Vehovta Lericha Kimocha." -- This statement seems to imply that the mitzvos which are bein adam l'chaveiro are somehow more important than the mitzvos which are ben adam lamakom. Hashem commanded us in all these mitzvos, and they are therefore all equally valuable to us. (I agree that He also gave us rules of preference -- e.g. if it is a choice between desecrating Shabbos and speaking loshon hora, we should speak loshon hora -- but we cannot conclude that loshon hora is somehow less important than Shabbos and we can therefore treat it lightly.)