Yes, I was looking for the same feature. I track days in which certain items happen using tags, it makes it hard to organize because the entire calendar box fills blue as if I had an entry when it was really only a tag. I feel it blurs the line between tracking items and actual entries.
Maybe instead of filling the entire box generic blue, an option could be made that it lists the tags within the box with the text highlighted the selected color (almost like a gmail calendar). If a diary entry is also included on that day along with tags then maybe an icon on the top corner could be used to indicate as such.