It makes sense flavor wise. Each character did have unique chapter tactics, so that just seems to fit the original idea. In all the games I've played with SMs over multiple editions, I've never taken more than one character anyway. You can still create successor chapters and use the character, but with Space Marines, you generally build around the tactics, not the guy. Hell, if I want Pedro in Iron Hands, I'm damn well doing it. Call them The Iron Fingers - successor chapter! Failing that, after just reading the new info, maybe that chapter decides on a new color scheme, or a nickname for their company that still counts as an original design.
Other edit. Successor chapters get chapter tactics, so the main reason for taking SC's is already given. So taking a captain or chapter master might make more sense.