Irrelevant, Obito has still shown bigger katon feats without kamui than the puny one he used against kakashi. Also, a continuous barrage of on tips wood branches WOULD cause a large amount of trouble to a kakashi that is TIRED.(which he was, as stayed in the kamui dimension for ages after the fight to recover.....) Your examples are extremely shitty as are your analogies. Obito clearly said that the puppet master seal was INTERFERING with his attempt to become the juubi's jinchuriki-this heavily implies that he thought about/tried to do it before. What better way to remove it than to get stabbed in the kamui dimension-as Madara would NOT see it occurring.(Hence he would still believe that obito was his puppet.)
This is completely different to the VOTE situation between Hashirama and Madara. Madara wanted Hashirama's DNA to further his plans yes, but it would have been FAR better for him not to be severely wounded by hashirama, hence we know he didn't throw the fight away. Plus, we saw both men use their strongest moves.(PS,Buddha,kurama) (Also, a man like Madara could easily fake his death even if he won-as he faked it in canon.) The reason it would have been better for Madara to not to be injured is due to the fact that he would have been able to do a lot more on his own, without being a crippled/weak/injured man for the rest of his life.(and possibly achieve his goals faster) It's blatantly obvious that Obito planned the stab during the fight. Only idiots think otherwise.