I have about 10 100 year old oak stumps that I rolled in the lake when it was built, and love them. Having said that, my experience has been that the structure I add gives me the ability to place the structure easier, and move it if I need to.
I've found that man made structure, added after the lake filled, really adds to the performance of my feeders. The cover seems to hold more fish in the general area, and increases my catch rate in those areas.
Personally, I'm not convinced it's an either or proposition.
