1. One is obligated to fulfill positive commandments and to be careful not to violate prohibitions. What is the point of putting yourself into a situation where you become obligated in a commandment?
2. Is the commandment in the act of putting it on, or in every moment that it is on you? If it is in every moment, how exactly is that measured?

1. You didn’t ask about obligation, and I wasn’t talking about obligation. You asked what the point is, and that’s what I answered. If you put on a garment with tzitzit, you have one more commandment.
2. It’s not in the act, but in your being clothed in it. The question of whether there is a commandment at every moment is not well-defined. There is a commandment to be clothed in tzitzit. As for the practical difference—how much reward you’ll get? I don’t know.