How is that worse than how weapons magically disappear now when you use a power outside of the set?
Because that takes a problem that happens half the time and makes it so it happens all the time instead. Personally, I think the half second of a character drawing their weapon looks cool enough to justify the slight penalty it might have on DPS, and the alternative, making weapons that always just magically appear and disappear, would make weapon powers feel empty and cosmetic (as someone else said, instead of drawing dual pistols, it'd feel like using blaster powers that just happen to make dual pistols appear in your hand for a second). There's something to be said for the thrill of seeing a group of enemies, hitting the attack button from a distance to draw your weapon and then charging in with blades swinging, and really, CoH isn't such a difficult game that redraw animation times make or break anything.
To answer that via an earlier quote...
"Now, I'm not saying this guy at Microsoft sees gamers as a bunch of rats in a Skinner box. I'm just saying that he illustrates his theory of game design using pictures of rats in a Skinner box."