Did they sell like KOTOTR? No, and some of that can be due to the small PC gaming market of the early-mid 90's because the Rouge Squadron games were platnum sellers on consoles.
Also.....dont think the OP said anything about sims, wich is why i suggest a "Wing Commander" like space RPG with Star Wars skin.
Wing Commander was a straight-up space sim in the same family as X-Wing.
Freelancer comes a bit closer to RPG mechanics, but still depends on player twitch skills over in-game character stats for success.
Just what elements differentiate a "Space RPG" from a Space Combat simulation?