Hell no. If you're adults with jobs, then go buy yourselves some proper gaming-PC's for gods sake. If teens can do it, then so can you.
"proper combat simulation and realism" is as dependent on graphics and physics as anything else, and I think it's awesome that BIS is putting more work into this in ArmA3 (Especially when it comes to physics). ArmA2 is filled with frustrating realism-killers and limitations that can only be fixed with new hardcoded systems, which will of course put new demands on PC's. Technology must go forward, compared to all stoneage console-ports that are dominating the market.
Optimization is of course important and I'm sure BIS knows this already

That's why we're getting a Community Alpha.