I take my KBT Pure with MX Browns to the office every day. Still using the original box. I leave a cable plugged into the computer at work and just unplug the keyboard end when I leave. Makes packing up simpler and quicker. Just put the board in the box and go.
I think they should have used Micro USB instead of Mini USB, because Micro is designed for a lot more insertions / removals, but in the end the Mini plug should last if you look after it (don't pull the cable at strange angles, etc).
If you're concerned about it, get a Filco TKL (fixed cable) or a keyboard with the socket flush at the back of the board (almost all 60% boards like HHKB Pro, Pure, Pure Pro, Poker 2, Filco Minila, etc, and some TKLs like custom Korean ones). Most TKLs have the cable socket in a bad position for frequent removal (Ducky, Coolermaster, etc.). The Matias Mini Quiet Pro uses a Micro USB socket flush with the back, but it uses Alps style quiet click switches and is not standard TKL layout.