Well you have to imitate Kirk.
Kirk's most profound feature are his mannerisms and speech. Those two characteristics are more profound and widely known than any physical trait any other star trek character has and is more recognizable.
He is arguably to most well known star trek character of all the series and movies and he did it without a fancy uniform or makeup. So there is something to be said for that.
Nope.
If that were the case they would have also not shown Piccard, and Spock who are also insanely recognizable and popular characters.
The image is also supposed to be for star trek day and celebrating all of it. Why omit arguably the most popular and well known character that launched the franchise and there since the start?
No, Kirk isn't popular because he was the only manly character on there. He took charge, he banged alien chicks, he had bravado, and he was a macho dude. That goes against everything in modern star trek and in modern Hollywood.
No, Kirk was omitted for being too manly and crass for today's weak willed, soft, pussy ass bitches.