I too agree with the disadvantages of a charging port (or even charging in general), but I don't think THIS charging port on the picture would accumulate much more dirt than e.g. a barometer sensor on any ABC watch.
The issue for me is more of having to have yet another charger on your desk or with you if you are going on a trip. Laptop charger, phone charger, bluetooth charger, camera charger and now watch charger. Great. What else?