You can't disentangle the two. The pound (even though it is doing badly now) has nowhere near the volatility of a cryptocurrency.
The lower the Steem value goes, the smaller the value of payouts will be. New people will be less attracted by that.
Further I don't think having a pegged note is any simpler than having a cryptocurrency on it's own. People can understand that different currencies have different values.
I really don't see any disadvantage to removing the Steem Dollar in that sense. People will go where the money is like I said before. Money is a great motivator to learn new things.
People will go where the money is -correct. So what does it matter if the payouts get low? I don't see any other social media platforms paying me a couple cents for a comment. We're safer to attract a userbase while the price is low, rather than when the price is unrealistically high, as people quickly get used to making that kind of money, and suddenly $40 a post isn't enough. This is a better price to grow at!