I must enter the fray :-) There is absolutely nothing wrong with just collecting/studying kodogu. I know several very serious collectors who don't even own a sword. Personally when swords went thru the roof, price wise; I turned my attention more toward tsuba (I had always acquired a few). I find it a very enjoyable and complicated study; perhaps more so than blades.
As far as displaying tsuba, I have a few on stands but most are in tsuba boxes and rotate them occasionally.
My basic philosophy is: collect what you like, but like what you collect.
Rich S