Going with your tongue-in cheek oldschoolness joke, I guess it's a relatively modern concept that serious work doesn't necessarily require a fake-serious demeanor. And yet clients would probably trust a lawyer wearing jeans less. Oh well, one step at a time, I guess.
edit: s/thanksless/thankless/
"There's a race condition in your implementation of pthreads (cake emoji). Bugs are dead. Thirty seven. So (walrus emoji). That causes your... You didn't release the semaphore. Semaphore aphorism smidgen genetic tictac tactic. The lock is dead. Lock. Locke? Deadlock. (cake emoji)"
Just kidding, that'd be too cruel.
Also on a more serious note, emoji can seriously help when discussions start feeling more heated than they should. Adds a little levity so people know you're not being a dick. Really important when you're both remote and only see each other once or twice a year.
Ah... the old "I'm not being a dick... I used a smiley" defense. :)