I get it. Crossovers aren't a novel idea of course and we've seen plenty of 'team-ups' even within canon.
Maybe what we haven't seen much before is completely transplanting characters from one series into another and make them native to it. Mixing your Trek, as it were.
Not sure if there's an audience for it but if it's something you'd like to see, probably the only way you ever will is if you write it.