Story Tweak
Actually, setting-wise I’d prefer to have the crash survivors be more primitive in their architecture and technology (taking inspiration from Riven), and to have had an ongoing and increasingly hostile struggle against the native life on the planet. Perhaps it’s this native life that wiped them out, and not themselves. This would tie in nicely with them being innately hostile and unsympathetic.
Maybe they’re still somewhat sympathetic due to the “aliens” crashing on their planet and possibly hunting and killing them, but still.