Since when is a four foot tall speaker big? It seems the majority of examples here are not really that big, at least in my world. Now, a six foot tall speaker at about my height - that's getting big! If one drives a compact car every day a full size sedan will seem large. If you drive a sedan an extended cap pickup will seem larger. I tend to "drive" larger speakers, so I was a bit disappointed in the ones mentioned as large speakers. I call a 3' tall floor standing speaker small; much smaller and you may as well get a monitor.
Wafer, some questions: What do you consider to be a small room, and what do you consider a large room? If you're calling these speakers large, then I'm wondering what you consider to be a large room? (Obviously, cultural differences apply, as many places in the world have far more restrictions on space than in North America. If this is the case, then my comments which follow need to be seen in the context of North American concepts of space in a home.)
Have you conducted such tests in order to arrive at your conclusions? I ask because I have conducted such tests and found that a moderate sized room like mine can be fantastic for larger speakers. The critical difference is not so much the room size, but the quality of the room, i.e. construction, whether it has windows, whether it is tuned, etc. In my case though the room looks rather simple, behind the walls are 7.5" of multiple layer construction, under the drop ceiling is another completely solid ceiling, a thick carpet pad is under the plush Berber carpeting, etc. I would prefer a smaller good acoustic environment to a larger and poorer one. The size is not the only, or even the major, factor in securing a good environment. I know one audiophile personally who has a cavernous space with lots of glass; he's fighting sound problems continually.
Have you simply received the "accepted wisdom" of audio which suggests that one must have a larger room in order to enjoy/utilize to their best larger speakers? At times I enjoy breaking such received "laws" of audio. When I was younger and into aquariums I was told that I could not do a smaller saltwater tank, that I needed at least 25-30 gallons to get it done. I didn't like that limitation, so I did my own ten gallon saltwater tank, and it worked. I have to laugh now when I see "micro" saltwater tanks at aquarium stores. What happened to the "law" of size imposed on tanks? It kind of disappeared when enough intelligent people said, "I don't like that limitation, and I think I can get it done!"
All things equal in terms of room construction and room treatment a larger room may be better. But a generalized principle that with quality gear a larger room is better will not do. It is easier to work with a big speaker in a big room, but it certainly is not impossible to do so in a more modest sized room. And I have heard a lot of great gear sound Ho-Hum in bigger rooms, and/or ones with vaulted ceilings. In addition, in a room which has been built for audio and is tuned the most minute distinctions between speakers, both small and great, are easily heard.
When Bill Dudleston of Legacy Audio brought the Helix speaker system for review (it can be seen in my virtual system pics) and set it up in the room, after blasting it at seemingly jet engine levels he turned to me and said, "This room has excellent acoustics. It is like a mastering studio." That was my goal in design and construction - to make an environment where the absolute best experience of the equipment was the reality. I hear huge speakers at their best every time I listen because they are in a quality environment, not simply a big room.
So, Team member Wafer, from my perspective your question (which seems posed more as a declaration) is provocative if you hold to it without exception. :)