Yeah, you can have both IF you luck into an athletic freak.
You don't have to be big to hit hard. Sure, it helps, but there have been many smaller guys who could lay people out. Mike Minter wasn't an especially big safety, but he could lay the wood with the best of them. Troy Polamalu being another.
When you start naming the best safeties of the modern era, for the most part they don't fit your mold. Most are in the 6' 200# range.
Ed Reed is 5'11" 200#
Troy Polamalu is 5'10" 207#
Brian Dawkins 6' 210#
The days of the old school head hunting safety are over. You gotta be able to cover to play safety effectively in today's NFL. Hell, the NFL has practically banned the old school head hunting style of play anyway.
You are correct sir. There is nothing in your post that I disagree with.
That said. We are talking two different things here. Rudi's S is rooted in fantasy. While your S's are all HOFers. Way to unbalance the scales by the way.
Teams are trying to get bigger corners and safeties. Why not take an athletic but undersized LB and experiment? Teams try strange things all the time. Ain't gonna happen. But that is only because I, or Rudi, are not in charge.