It's one of those terms that are unnecessary but people say out of habit. If you state your position on something, then it's obviously already your opinion, you don't have to add IMO. It's just that some people read "I think Superman stinks" and go off on a rant about how that other person is so wrong to think that and that it's just an opinion and Superman actually rocks. Then you have to put "IMO" after everything you say so no one gets offended by your opinion. This way, when someone snaps at you, you can point to the "IMO" you typed and say "Shut the hell up, troll under the internet bridge!"
DC Direct has some beautiful designs but lack in the articulation aspect. If your not into poseing your figs ever so often I' say pick em up. I've recently gotten into collecting the Kai Asamiya Batman figs from DC Direct, these have no poseability but I love'm none the less. they make great, inexpensive mini staues.
IMO=In My Opinion