You would never be able to use "that ability" whenever you want. Either it takes combo points or it has a 10 second cooldown. And combo point chararcter by default are built with legitimate decision making gameplay (multiple finishers for different situations). So yeah, I find them a step up from regular old DoT stackers.
I agree that combo points are an interesting melee mechanic but the multiple finishers option never actually happens. There is a best one, where the others can be legitimate choices, and better in certain situations but since we are limited in skill points, you can't take more than one without being less efficient somewhere else, defeating the purpose.
They are different, just not "better" for me. Could be much more.
When looking at Rogues or something in WoW, they use a combo point system but have a huge array of options for how to spend them that are all legitimate at some point. Someone like Luke Cage's are just do you want more damage but a terrible animation, less damage and a better animation, or even less damage and some dodge rating for X seconds.
I actually really hope we get a good combo point character (and by good I don't mean ttk).