Why did Stargate's human space program build large battlecruisers rather than small dedicated gunships?
Short answerThe proposed explanation is the integration machinery needed to make human and several alien technologies work together within one hull.
NotesThe proposed explanation for Stargate's large human battlecruisers is the machinery needed to make technologies from different origins work together. The ships combine human, Goa'uld, Asgard and Ancient systems. A common technological basis would make compact gunships easier to build. The BC-304 example instead raises the problem of accommodating several technological traditions in one hull.