TL;DR
In 2.0, the ability to perform multiplication/division/etc. was added when setting constants - when placing a blueprint that has parameters that are constants, it would be great if they also supported mathematical operations.Why?
It feels natural for this to be supported. In fact, I immediately tried to use it, assuming that it would work because it works when setting other constants, and when it didn't work, it felt like the game was broken. I can't think of any gameplay-driven reason why it shouldn't be allowed there.Also, while you're at it, can the text field for constants in blueprint parameterized values be made a bit bigger? It's very small right now, making it difficult to see large numbers (or really any significant amount of text).