The trip would definitely benefit the airport in some way. Derry airport, being the small regional airport that it is, wouldn't have management with the same experience as the DAA, or know that the airlines offer as well as Willie Walsh or MOL, so these events allow the management to see what other airports offer, what their USP's are, how they offer this, discounts, how airline operate, what deals are signed and how.
Even if nothing comes out of them, it establishes Derry on the table for airport's looking to expand and is also like a very helpful management training course.
Never underestimate these events.