Truth is, in the 1960s you didn't see many non-whites with regular roles on TV. Granted, Uhura and Sulu weren't exactly integral characters, in fact we did have other communications officers and helmsmen throughout TOS. But, it got them recognition all the same and there weren't many other shows offering inspiration to African Americans or Asian Americans, so it's the symbolism that counts.
If TOS wasn't the first interracial kiss, than what was? Just the fact there was an interracial kiss on screen is a pretty big deal, even today. Hell, when Enterprise introduced a love interest for Mayweather in the Demons/Terra Prime story, a white actress was cast but make-up darkened her skin because she was Mayweather's love interest. That was pretty pathetic, especially for a show filmed in 2005.