I was examining, above, how the Nightwing & Red Robin suits represented the moods and persona of the wearer, and the Jeans/T-Shirt look are basically there to represent Conner as the casual guy, the friend who you can talk to no matter what - sort of a less majestic version of the mood that Superman himself is meant to radiate (if A-SS is any indicator).
Now, Bart's new costume represents the fact that he's regained his life and his youth, and so donning a 'Kid' identity; Tim is covering his entire head and strapping belts to his chest as if to contain his intents and emotions.
Since he's on a finding-himself journey, but a more positive one, perhaps Conner should try out several new looks. What about a more scientific costume - the sort that Luthor would have designed if he himself had been Superboy instead of Clark? Or a reworking of that suit he was wearing back when he used to have a goatee and crushed on Cass Cain.