I think the main problem is the first Robocop already told the best and most compelling story with this character-- his creation and Murphy's gradual reawakening from within-- and already had the best villains (in Boddicker and Jones) and coolest action sequences (Robo vs ED-209, Robo vs the people who killed him, Robo vs his own police department, Robo vs an entire freakin warehouse of armed bad guys...)
I think The Series
managed to do excellent work with the RoboCop character, by exploring his existence as a hybrid being who was neither man nor machine, who remembered the life of Alex Murphy but could never be Alex Murphy, never return to his family or even let them know that a part of him survived. It also developed him by giving him distinct relationships with various other characters. Although it took a while to get the hang of it. The early episodes tended to marginalize Robo by having him frequently damaged and taken out of action, with the focus more on his supporting cast, but over time they really enriched their exploration of his character. I don't agree that an origin story is the most interesting story to tell about a character; quite often it's one of the least interesting, because there's so much emphasis on establishing how a character became who they are that there's not much room to explore that identity.
Indeed, what disappoints me about the original film is that once RoboCop remembers his past, he's portrayed basically as Alex Murphy in a metal suit. I'm much more intrigued by the series' version, where he's not just Murphy but a new, unique entity formed from the blending of Murphy's incomplete memories and psyche with RoboCop's logical programming. It makes him a more distinctive and complex character, a being caught between worlds and identities, not fully a man or a machine and struggling to reconcile the demands of both. (And kudos to Richard Eden for the amazing way he conveyed so much of that internal struggle so subtly, with the barest hint of expression and intonation -- a skill that nobody else since Leonard Nimoy has ever mastered so well.)
And sure, R:TS didn't have action sequences on the level of the movies, but action is boring without worthwhile characters and emotional stakes, whereas stories that have those things can be entirely satisfying without needing big action.
(That said, I do have a soft spot for RoboCop 2
's climactic action, since it's probably the last great stop-motion animation set piece in cinema history. Sure, the underlying plot is silly and the characters superficial, but you can say the same about a lot of Ray Harryhausen movies.)