JD, I got the second bowl set with the special offer this year and I got the extra rice cooker and butterfly too. Like you, I haven't used them and probably never will.
I love having the second bowl as I am often not organised and forget to mill the sugar or something before adding the wet ingredients. I do find that I often use both bowls when cooking and it certainly gives you a lot of freedom. Like others say though, it isn't essential and I wouldn't have paid full price for a second bowl set.