A little harsh - after TWOK he became a well-rounded person, with his own friends, credit cars and keys...
And yet him and George still had to share Melllvar's fan-script...
Chekov was the O'Brien of TOS, constantly having the "he must suffer!" scripts written for him.
Sulu on the other hand, he was a sponge for whatever cool hobby they thought they could saddle him with for a particular episode, only in order for it never to be mentioned again!
Bearing in mind the decor of Kirk's apartment in TWOK, I think it was a missed opportunity to have Sulu give him a genuine 20th century antique firearm for his birthday!