I'm not tunnelling to my home network in order to use the banking app. I'm tunnelling to my home network as part of my general way of accessing the internet. My banking app isn't the only thing running on my phone while I use it.

I don't want to have to turn it off just to use the banking app.

if it was decently written by a sane programmer

Better hope it is then, I guess.

On the other hand, there is significant security value in the bank being able to see the actual IP of connecting clients.

Can you expand on that?