[X] Secondary capability, medium range, decently armed. (Light Cruiser: ~400k)
Two reasons for this:
1) We are Starfleet. Starfleet wins wars through science just as much as through military might, just remember a Galaxy class being destroyed in first conflict with the Dominion in DS9 by Jem'ha'dar weapons going through their shields. This was solved, off screen, in like months in universe. Thus a light cruiser that actually can be there during a war, scanning enemy ships, detecting cloaked ships/mines and doing the usual Star Trek technobabble stuff would save lives and help other, more dedicated warships win.
2) Again, Star Trek verse. How often do we see some anomaly that actually requires decent shields to survive at first, or to get near enough, or a torpedo launcher to modify a torpedo into something extremely none torpedo like? How often does the shield dish gets modified to do some crazy stuff? Well, all this requires, respectively, a torpedo launcher with torpedoes and a shield dish of decent strength, things a science frigate is unlikely to have.