I hear you Clive. Somewhere in the archives of here, RFF or photo.net there's a reply from me from about 5-6 years ago on a similar thread saying almost exactly what you said here. And with a similar attitude. Then I got a hold of one and used it. When I throw my M2 or MP into my bag with my 50/2 Summicron DR attached I'm going out to shoot knowing what I've got and using that tool to get what it's best for. Otherwise I'd take one of my many other cameras. If I take out the Holga, and only the Holga, my mentality is different, my goals are different. It's almost like another media, or at least using a VERY different brush, and the results are different (not always better, but sometimes ) because of it. Changing negs in photoshop that I shot with my Leicas is making Leica to resemble Holga-like images. Going out with just a Holga and out to shoot "native" Holga images gets me very different results and is a change or a diversity in my photographic goals and mentality I enjoy very much.
And I hear you, but beg to differ. I will stick to my M2 and you may stick to your Holga. No way will you ever change my mind, as my M2 is part of me. End of conversation.