While not initially developed as part of its initial fleet, the deWulf Navy immediately began design studies of a warship larger than the destroyers currently in service. Memories of tonnage races in past informed the designers that larger, more capable hulls would be needed Soon™. It would be better to have the concept refined before the need became real, and the funding taps opened.
An evolutionary hullform as opposed to a revolutionary one, the light cruiser effectively has the aft half of a destroyer attached to the rear, half of that on either side of the main hull form. Internally the changes are more complex, with systems having to be rearranged either because they take up more space, or because they need to be located elsewhere. Engineering spaces are the root of the larger changes, with some engine rooms expanding to fit additional drive coils (the engine rooms in the center hull). Weapon mounts are the other major change; with a wider hull form, having everything on the dorsal and ventral centerline is no longer entirely practicable.
I had a good design for what I wanted deWulf heavy cruisers to look like; I had a pretty solid (eventual) concept for what I wanted the destroyers to look like. What bedeviled me for honestly a year or more was trying to come up with some kind of transitionary design between the two. After a lot of bashing my head against the wall this finally gelled together as a good transitionary concept (after I started playing around with capital ship hulls, oddly enough!). While it’s still not a complete concept, I finally got a hull form I was happy with. That’s good. I can work with that.