For the sake of discussion I'd like to at the following observations:
USS Challenger, Galaxy-class, and IRW Tomalak's Fist endured trans-slipstream, non of which are streamlined.
Neither is the Enterprise-J, though.
In STO, every single playable ship is capable of attaining quantum slipstream velocities, for game-mechanical reasons. That includes the NX-class light cruiser and Type 8 shuttle craft. :-)
Personally, I favour streamlined designs. It looks cool.