I totally agree. We have people involved (myself as one) who compose in Markdown externally, and then paste in our formatted responses. The current implementation for large text fields makes a huge problem for that workflow.
Now, imagine you have a three page document written and formatted in Markdown - how do you even get that into a Podio app? Paste it to the activity stream? It doesn't seem right.
I'm facing this issue right now, and almost daily.