Some food for though, and sorry if this was stated elsewhere, but perhaps the underlying ride system for Stark Flight Lab might have been what was originally planned for the Quinjet Avengers E-ticket that was nixed due to Imagineering not being able to crack the code on capacity.
But because of the amount of R&D that went into the Quinjet ride system Disney wanted to show it off somehow and this is what they settled on. Another reason for this could be that since Infinity Defense is more than likely taking up far less space than the Quinjet attraction was going to and perhaps they figured this was a creative way to properly fill out the 3-4 acre expansion pad since its the last expansion plot DCA has within current park boundaries.