The Gun Mettle update chose 3 taunts and each one for a reason.
The Cossack/Kazotsky Kick taunt was originally just going to be a Heavy taunt that lasted for around 6-7 seconds until being changed into the new conga group taunt for all-class, and potentially could have been scrapped but the taunt itself was in high demand to be added and has been hyped up.
Box Trot was likely added to cater to the 'friendly' aspect of the game, which Valve seems to really support especially with every single Love and War taunt on the website displaying a Red and Blu team member. And just a complete guess but the Skullcracker seems to be made specifcally because of that super duper funny joke people do by killing themselves via console when doing a high five. (Just look at the winner of the Saxxy 2012 Replay!) But still, the Box Trot seemed to be the least special but still wanted by fans in the workshop.
The Soviet Showoff/Proletariat Posedown was added in favor of the poor Heavy, who had no taunt for himself. (If you haven't caught on, the Heavy got somewhat special attention in the update.)
So this taunt still has a chance, it just wasn't it's time yet in order to make room for others. And if the improvements I mentioned in my other discussion are included and this taunt gets enough people wanting it, It'll be in before you know it.

TL;DR: There were far superior choices for taunts during the Gun Mettle update, not so much now.