Do you have an example of what you are aiming for?
Like another program that allows you to draw in it?

Also one thing to note/remember: Holotech Studios is only a small indie development company, so they need to choose well on what to devote their programmer's attention.
Some features, while neat, are only usefull/interesting for a small part of the community, while others might require a lot more time compared to the advantages /features they bring. Idea's like this aren't forgotten, they are written down on a list of things to do when the team grows, or when they can combine it with something else.

Manycam, Webcam Max, etc.

There is already an overlay for text in Facerig, this would be an addition to it.