Well, let's give it a try at lest...
FLCL is truly an unique work, with an unique style and appeal.
I really like the deep yet simple-pletending psycological characterization
of Naota, Mamimi, Ninamori on top.
I think Mamimi describes the way modern Japanese gals [kogyaru] can be in a very
effective way.
Thinking of Naouta and Mamimi, I really see a fil rouge linking Eva,
Love&Pop, and FLCL.
Emptyness, discommunication, shutting away from the reality.
These are very aspects of the modern juvenile depression disease.
I also liked the character of Kamon, as a 'portrayed of an Otaku', very much
Otaku no Video like.
It seems the focusing of the relationship between parents and children is
one of Anno main interests along with all Gainax.
You know, Noriko, Jean, Nadia, Shinji, Asuka... it's all about fatyhers and
sons in Anno storytelling.
My first impression was that FLCL is quite different from other Gainax (Anno) works
except for possibly Love & Pop due to the "emptyness, discommunication,
shutting away from the reality" themes that you mention. I would also add
"denial" and "transferrence" to this list, particularly for Mamimi.
However, in terms of parents (grownups) vs. children, in contrast to Nadia, Gunbuster and Eva which make this intereaction a central theme, FLCL almost seems to downplay it to the point of trying to make it *apparently* non-existent.
For example, instead of worrying and being troubled about heir parents, Naota and his female classmate instead pretend that it does not affect them, and indeed without the the Oedipal references in episode 4 it is almost easy to forget that Kamon and Naota are even parent-child at all.
The main grownup-child theme in FLCL seems to be the children's perception that grownups are irresponsible and sources of nuisance/bother.
This makes FLCL maybe more 'modern' than all Gainax works before Eva at least, which I found more 'dramatic' from the point of view of this content.
Till Eva, we had characters doomed with their parents ghosts.
Following the path Eva -> Love&Pop > KareKano, Gainax managed to fully merge this deep theme into a more realistic and less SF-dramatic scenarios.
Thus I regard FLCL as some kind of fusion of all the above.
And again, we see the total apparent meanigless of those children->adult relationships is of course balanced by Naota's (secret) wanting to be with Haruka, and Haruka repeatedly inviting him and then saying that he is "still a child" -- an interaction that I think is not given enough attention by most people. (Anything in FLCL that is repeated twice or more -- even in seemingly unrelated
places -- deserves closer scrutiny.)
It almost seems as a way for children to reject the way of growing-up proposed and symbolized by current adults, and struggling to find their own way to get adults.
Then again, back to Anno's and the whole Gainax themes, we have the famous topic of the developement and real power of human science, from the young enthusiastic point of wiew of GunBuster, to the someway romantic approach in Nadia, to the more mature and doubtful ideas in Evangelion.
And then, depression.
This is Anno very mind, but I also assume all that as a basis for FLCL
raison d'etre.
FLCL is a Gainax work even more than a Tsurumaki's work.
I can see Sadamoto's mind, Anno's mind in that.
Not only as for the homages and citations issue.