Aero wheel on front, regular on back - why?
I think this is being over-thought. Aerowheels on messenger rigs have nothing to do with performance, quicker locking ability etc. etc. It’s just the new generation mimicking the older generation, trying to be cool.

When I was a messenger, many of us were pursuing racing careers.  The messenger gigs were essentially poor man’s training, and a steady source of income- since sponsors didn’t give you enough to live even on ramen. When fixies started to become cool, the next generation of messengers were mostly posers. I say that with love- spend enough time on the bike, and the most blatant, fashion-conscious poser will become an actual rider, and to their credit, that’s exactly what they did, and many of them ended up very cool people in love with the bike. But sometimes some lame things from the early part of that process can survive, and even end up being the norm.

So it was with the racer affectations such as aerowheels. A lot of those guys looked up to the older messengers, they’d see them around town on their race rigs when they weren’t working, and monkey-see-monkey-do.

I remember once I was trying out a full-carbon (no padding) saddle from a sponsor. This was bananas back in the day, because even though carbon wasn’t exactly new for frames, it was cutting-edge for this kind of application. Anyway, I ran into some young’ns down at the shop, and like two weeks later, there was a full-carbon saddle craze among the hipsters who were on the job. That saddle was horrible even with chamois- I basically tried it and sold it. I can’t imagine what it must have been like with jeans and being weighed down with fifty pounds (24 kilos) for the mail run. But they rocked ‘em, god bless those crazy kids.