I think Evangelion (and a bunch of other media) have a lot of potential for philosophical analysis, and while this is no means a bad start, there are more concepts that could be incorporated or be applied.

Come to think of it, we could even bring in some more Heidegger to talk about ready-to-hand vs present-at-hand in regards to piloting EVAs and (I can never quite remember what it's called) the totality of objects/tools/referential totality.

The EVAs appear both as present-at-hand objects observed passively from a distance that people study and ponder about, but to pilots after some exposure they appear ready-to-hand objects; not merely objects, but tools. One of the greatest revelations of the series comes from how the nature of EVAs as humanoid entities is revealed by a transition from ready-to-hand status to present-at-hand status when an EVA 'breaks' and part of its body is revealed. Like in Heidegger's example of the hammer, it is when the tool 'breaks' (becomes nonfunctional) that we begin to question/observe/postulate about what it is and how it functions; the answer of 'what is an EVA' only becomes relevant to the audience and the pilots when our perception of the EVA transitions from ready-to-hand to present-at-hand.

This can also be tied to referential totality, and the idea that all objects (and people) are connected to each other through a series of implied references. If there are EVAs, there must be someone who pilots them and there must be someone who makes them, tools, research, scientists, engineers, support staff, etc.; a complex web of human interaction that all connect to the EVA - and thus the EVAs serve as both physical manifestations of human interconnectedness and as a symbolic manifestation of human connectedness. That symbolism is of course only further enhanced if one takes into account the with the knowledge of what EVAs really are.

We could even talk about Phenomenology and the idea of the body schema, and the way physical objects can allow one to 'extend' their perception of their body. EVAs (like all 'mechs') are perfect example of this through the way LCL fluid and plug suits allow the pilots to synchronize with EVAs; to experience the EVA's body as their own. We could talk about the body-subject, the acknowledgement that the body is its own kind of conscious entity with instinctive desires, reactions, and own sense of rationality; the pilots train to instill in their bodies the (muscle) memory needed for piloting; to have their body which is a subject in itself to remember and react to the world around them. We could maybe even bring in AT fields as a product of the spiritual body's (or soul if you prefer) memories, actions, and reactions within the physical world; how the memories of pain and fear the spiritual body has suffered are used to create literal barriers for protection.

There's just so much opportunity.

Edit: I think I should clarify that I don't think you (or anyone) has to include all these other elements, just that I personally think they're interesting and would have been delighted to see them discussed.