Everyone in TF1, including the robots, were well characterized. The problems with the portrayals came afterward and on two fronts. First, Bay sacrificed characterization for action. Not a bad choice, per se, but there's only so much action he can offer before the general audience considers it repetitive, routine and droll. Second, Hasbro sacrificed characterization for pushing product. Even if you put aside how new robots were introduced in such a way that the audience is supposed to pretend that they were there all along, the only reason Ironhide and Ratchet were relegated to the backdrop in TF2 and then each killed off in TF3 and TF4 respectively was to make way for said new robots. That kind of cynicism does little to encourage the audience to connect with the characters, let alone engage with a franchise.