I’m not sure how or why grape became the default. For the longest time, I thought I didn’t like PB&J. But ever since trying it with strawberry instead, I understood the appeal. It’s so much better, and now I find it weird that the combination isn’t more common.
M&Ms did a promotional thing for one of the transformers movies, it was “strawberried peanut butter” and it was fantastic.
They’ve got PB&J peanut butter m&ms out now. I forget where, but I got a carton a couple weeks ago.