It is of course true, that great technique does not automatically make a great composer.
On the other hand, technical skill enables a composer to express what is required for the film more easily.
I think, Hans Zimmer is a good film-composer for the energy, the drive and - yes - also for the emotion that his tracks contribute to films, but if he knew more techniques of expression than string staccati and swelling string carpets (sorry Hans! Only metaphorically speaking - I know I´m being unfair here) he could be much better.
For example, I would have found the dramatic track Donethur linked even more dramatic, if it was less steady in its way to the climax. I also think, the track would require more atonality. That is what I think of the whole Inception soundtrack. It really drives the film forward and gives a lot of energy and emotions, but it lacks the disturbance of the situation of travelling in dreams.
On the other hand, I really like the emotionality of "Time", although it has these swelling string carpets again...
I think Zimmer has introduced some good things into scoring films that were unknown before him, but he is not as widespread in expression as many of the "older" composers (and even some of the younger ones like Desplat) are, which sometimes gives (at least me) the impression of "all Zimmer scores sounding alike"