This reply sounds like you think Den of Villainy is restricted to "concealable" craft, including Dragonfly. It is not, as noted in the original post. So this is an oversight I suppose.
Uhh, maybe I misunderstood...
Den of Villainy has the standard starting conditions for infiltration missions, meaning it restricts outfits, equipment and soldier types (no robots), but not craft. This is the same as with Cyberweb Recruitment and The Special Client, but unlike some missions which
do also restrict your craft options.
I don't feel that this mission is too easy due to having more people, but it goes somewhat faster, which is a plus in my view.