"The only purpose I see is unloading magazine while cycling lever...."
Agreed and this is why I like it...Probably one of the most high risk times when operating a rifle...especially a lever. If possible, I always put my bolt rifles on safe before I load/unload the chamber. Running 10 rounds through the action is a lot more exposure.
I also prefer the cross bolt safety yet only one of my Marlins has one which is 1894 .357 stainless.
