To be fair that's just how defense expos are, not just IDEAS. I've been to Modern Marine, worked a booth at AUSA, been to ISDEF and Eurosatory. They're all the same. Look at China's recent Zhuhai Airshow, was there much that wasn't shown before or we didn't know about? J-31, J-20, various armored vehicles, UAVs and anti-tank weapons... it's all stuff we already knew about, some was only just being shown publically or officially, but we already knew about practically everything at the show.
Expos like these (
this one from Poland - link to the thread) are about impressing domestic audiences, international prestige and military contracts for gear that is often experimental or out-of-pocket for the company and they need to impress the military to recoup some of their losses, or else the R&D and development costs are largely wasted.
I've worked a few and been to plenty, they're all about money and impressions, but showing off new or previously unseen gear isn't much of a priority, and will typically be done behind scenes away from prying eyes.
