I agree with skaianDestiny. Players are free to choose either play the tutorial and get a fixed starting squad plus some randomized soldiers that were (so to speak) recently arrived. Either skip the tutorial and get a fully randomized starting squad as planned.
Otherwise, there are reasons in Komandos` suggestion.
This solution will please those players (and I think there are a lot of them) who care about the "role-playing" component of the game (because why all these renaming of names and surnames), plus it plays for emotional involvement: hey, this Sebilian just killed my stormtrooper, who was a veteran who survived the siege of the original base! How on earth did that happen?