Integrated rudders (as used on Epic and Mirage kayaks) - why not on pedalboats?

I've observed with inerest some of the rudder solutions used on pedalboats, and was wondering what the pros and cons of an integrated rudder might be?

I have seen such rudders on Epic and Mirage kayaks, and from what I hear, people are very satisfied with them. Supposedly, they produce very low drag, are self neutralising and have good steering response. I've never tried one, but have often wished I had one when getting stuck in weeds or reversing into something...

For those who haven't seen one, this is the only pic I could find:



Cheers