It's important to me. There's no reason for them to lock editing in my offline BeAGm mode other than them sending me the message that it is their game and I'll play it as they like. I don't like their ratings, I don't like their progression, I want to tweak as I see fit as I go along.
I stopped buying the EA Hockey series b/c once I played games that weren't locked (The Show, NBA2k, NCAA Football, Madden) I realized that even though my favourite sport is hockey, and I'm OK with the graphics and gameplay, it does not have the same replay value if I can't tweak. And with the franchise mode I found I was constantly restarting my franchise b/c of the locked ratings.
The only game I buy that has ratings locked is FIFA - and that game is a lot more fun to play than hockey.
Frankly, it went from a 'no buy' to a 'buy' as soon as I heard that ratings in offline franchise modes might be editable. And now it's back to 'no buy.' Without that single feature I might as well pass and just rent the game and play a season with it b/c it won't be worth it to me to purchase. It may sound silly to some, but if you're an exclusively offline, franchise mode player it's likely an incredibly important feature to have available. For me it makes all the difference for my enjoyment of the game, and my decision to purchase the product or not.
And it's especially galling that you can't edit in franchise mode b/c there is simply no reason whatsoever that it is locked.