We all know giant mods like during OFP-times cant be done anymore, one single tank for ArmA II takes more effort then 50 addons for Operation Flashpoint, mainly due to the texturing.
Big mods like the Invasion 44 couldnt be released for ArmA, instead got ported for ArmA II, and in all likelyhood will be ported again for ArmA III.
Why should Addon makers bother for ArmA III to even start? The time the mod community starts rolling, the next game is due for release anyway.
Look at the addons that have been released, 90% are ArmA I or even OFP ports, or the infamous "Special Forces Reskins".
Is there any way BIS could steer against that? Release more powerful / easier mod tools?