I'm one of the people you don't understand

as I've mostly been using old manual lenses on my MFT cameras for a few reasons...
1. They're cheap

I'm lucky enough in that I'm comfortable and I can afford any
thing I want but I get a kick out of using cheap gear

2. They're... just... lovely

I think that manual prime lenses just look gorgeous, well, some of them do to me

3. Old manual lenses have end stops and markings and I find them a joy to use whereas personally I think that no end stop and no marking FBW lenses are soulless joyless things and to be honest when I use them I don't really enjoy the experience.
Yes, an adapter adds bulk and a little weight too but my Panasonic G1 when fitted with an adapter and a 28 or 50mm lens is still a very significant bulk and weight saving over my now sold 5D no matter what it's fitted with.
Manual lenses and adapters are just a different way of doing things and in fact I now use them on my Sony A7
Random pictures taken with old manual lenses...