Is the structure of Memento (as a completely random example) a big new idea, or a small one? That's what a lot of people ask us to discuss. To bring big new ideas. But the problem, but also the good news around this issue is - this needs to be looked at from a different perspective.
You can only judge the amount of meaningthat an idea has to you.
How much meaning or relevance does it have for you? That is the only way to measure a new idea. How much does it mean to you? How much impact does it have - to you? The new feature in multimap. Is it a radical idea, a big idea, a great idea. We cannot say. But if it changes the way you like to use it - then its a good idea. If it changes how you live your life (somehow!) then it's a great idea.
In other words, if you like it, go for it. It's great!