I came to the conclusion that footwear selection is often seen as secondary to some of the other gear being used..
Let me clarify my thoughts a little. Most river banks are damp and greasy. Rocks can be sharp and spikey. It is probably one of the most testing places for any type of footwear. A slip on a river bank could have very serious consequences in both the short and long term.
Previously, I found myself in a situation where I had worn wetsuit boots or slip-on shoes, and there was even a phase when sports sandals were popular. When I began paddling, options for footwear were quite limited.
Primarily motivated by the necessity to keep my feet warm, the preferred footwear at that time would typically be a wetsuit boot commonly used by divers.
Things have come on a great deal since then.
Fortunately I have never had a case of losing shoe when swimming but it can happen.
Good points Phil, and yet good shoes are in short supply (well, a choice of good shoes anyway!).