I play games SP only, and don't care one whit what others do in their games. What does fair even mean when an experience is entirely your own ?
But my general position would be to always allow players choice where it is practical and reasonable. Not doing so often reduces the appeal of a game and the reputation of the developer.
I think "hey - it's a single player game and you can do whatever you want" is generally really healthy attitude and I completely agree with it when it comes to modding games, choosing difficulty, cheats w/e. I think there are 3 aspects you should take into consideration:
1) it's not single player only game
2) even if you are the only person in the world who knows, there is a sense of satisfaction in knowing that you started from same position as any other player and overcame greater challenges.
3) there are people like me - who are really bothered if they didn't make their char as strong as they could when they could have and will spend 30 mins + just sitting there and rerolling. It's not a fun experience. There are reasons why RPG trends moved away from random stats.
I believe fixed starting stats would make for a better game, but more that I think about it, more convinced I am that they will go with DnD 5e rules.