Wemmick is pragmatic because at work be keeps to himself, but at home he lets loose and knows how to have fun.
Through practicality, Wemmick has learned how to survive in London, in the bitter, rotten underbelly served by Jaggers’s law firm. Wemmick operates pragmatically and practically.
Wemmick acts very differently at home then he does at work. That again, is practical. He would not last long if he cracked a smile more often around the austere and gloomy Jaggers.
I found him to be a dry man, rather short in stature, with a square wooden face, whose expression seemed to have been imperfectly chipped out with a dull-edged chisel. There were some marks in it that might have been dimples, if the material had been softer and the instrument finer, but which, as it was, were only dints. (chapter 21)
This description of Wemmick seems to indicate that he has fun sometimes. When Pip visits his house, he realizes that Wemmick keeps his two lives very separate. He is a completely different person at home, with his flagstaff at the Aged Parent.
“I am my own engineer, and my own carpenter, and my own plumber, and my own gardener, and my own Jack of all Trades,” said Wemmick, in acknowledging my compliments. “Well, it's a good thing, you know. It brushes the Newgate cobwebs away, and pleases the Aged. (Ch 25)
There is very little practicality about his personal life, and interestingly enough that is practical too! After gloomy days, it’s good to have a little whimsy.