It's nice to see you posting around the place again, @Evil and Chaos! I was recently looking into your EA Titan game as an interested lurker!
Like @Kyrt says, I think people (especially new players) are pushed a little towards mechanised infantry because of the similarities between EA and modern, mobile warfare. And, after all, at 6 mm scale, individual vehicles are much more distinctive than individual infantry models. Although I also might prefer a different aesthetic to the current flittertanks, I think @Kyrt has a good point about if the variant flittertank armaments were available: having a cohesive range to start gives much stronger motivation to buy into the range. Maybe an easy solution is to reuse the hulls and just produce the missing weapon/turret upgrades as a separate mould? Just as another idea floating around out there

@moredakka I know what you mean about modern Eldar vehicles! I think maybe the real problem is that GW produced a really great theme and we just want them to come back and look after it properly
For me, the key element design of the Eldar tanks is the bat-wing-like aspect and I think the motif of swept-forwards bat wings is IP-safe (due to its commonness, multiple interpretations, and due to, well, bats). Earlier, I posted a link to a Lego reconstruction of the Lego Movie Batwing as a design theme I really like personally, particularly the shape of the wings and the wing spars. Incidentally, being black (and really dark grey) and interestingly-angled, they made me think of stealth plane technology which I think was an intentional part of the recent Batman vehicle design teams.
So, my suggestion is something similar to that design: to me, it seems distinctive, similar to the old design (without copying it outright), uncommon in the 6 mm miniatures world, and stylish in its own way.
Anyway, some food for thought,
Thinking Stone
As an afterthought, maybe it would be interesting to have a poll about Eloi vehicle design themes?