I am raiding for a challenge, 16man gives it - 8man doesn't.
HM 16man TFB wasn't that hard... And I'm glad that NiM 16man EC is literally a nightmare so far. Mad props to those guilds that are sticking with it. It's a pain in the butt, but that's the way I like it.
I agree that there is a disparity between the two raids but can one actually make 8man as hard or harder than a 16man group? It seems unlikely as 8 people are far more easily managed and its less strenuous on heals. I doubt this could be changed unless BioWare enforces that you ALWAYS bring one sub-par player, where their sole job is to get hit by a) red reticles (ZT), b) stand in the wrong shield (FB/SC), c) jump into red squares (CV), and d) AOE's under the purple shield (Kephess), and e) only use basic attacks. Unlikely.
I think additional rewards (not just increased loot) would be awesome. A different title, an extra battle rez in the fight (please BW), extra chance on the tank mount, etc.