You are right--just form memory, O'Hara was in more episodes with more dialogue, and played a larger role than Sulu on ST. Yet Takei thought, "I am...a captain!!"
Takei contributed nothing to TOS. He was cast entirely because of his ethnicity and only remains in the spotlight because he whores out his sexuality in the media for attention every 5 seconds. If he was a straight white guy the world wouldn't give a shit about this bland extra from a 60s action show. He's a guy that's built an entire career milking his personal life for attention, whether it be who he's feuding with or wishes to marry. This is to cover up how otherwise talentless and uninteresting he actually is. Not to mention that his camp "Ohhhh myyyyyy!" persona does nothing but set back
the media's perception of gay people, for all his pretend campaigning.
It is insanely unfair that George Takei is more famous than say, another recurring non-regular Trek actor like Andrew Robinson. Who actually is
a superlative actor with interesting things to say (A Stitch in Time).
Oh, and Takei's performance in that Voyager episode was an embarrassing disaster that made all his bitchy comments over the years regarding Shatner's acting even more laughable.