This might be where a lot of the controversy is arising. I think that hardware designers feel quite simply that hardware just isn't software, and all the same rationale may not apply:many people would love to claim their work(s) are "open source software" to get all the benefits of community, support, innovations from users - but if their software doesn't allow commercial use, it's not called open source software - same goes for hardware. it's something else, and that's fine.
Software: Most open source software creators are not trying to sell their product.
Hardware: Almost all of the open source or open source wannabe creators are trying to sell their product, or at least that's true in the current context of open source hardware businesses.
Software: A large proportion of open source software is designed by several to many people, usually in widely varying levels of contribution, but equal level of risk (zero).
Hardware: Most kit/niche hardware business product are designed by one or very few people, and often involve long development and prototyping cycles for a non-zero cash outlay.
Software: The source IS the product. The idea being exchanged for free is the same as the item being exchanged for free.
Hardware: The source is a free idea for a item that has material cost and value.
Software: Distribution of both the idea and the product is essentially free.
Hardware: Distribution of the idea is free, but distribution of the product entails many logistical problems -- investments, physical space and handing, time consuming assembly.
Software: Everyone distributing open source is on equal footing. The product maintains value independent of the distribution channel. A large entity taking the sourcecode and redistributing it does zero harm to the creator.
Hardware: The playing field is wildly uneven for hardware production and distribution. A large entity with closer ties to production and less logistical and cost problems has potential to seriously harm the original creator financially. Unlike software, physical devices can be made in varying quality levels and shoddy quality can dilute the brand.
Based on all the above, can hardware really be treated exactly like software? I think there is a lot of pressure for hardware developers to be open source right now. It's considered the "right thing to do" and "better for your customers." It's possible that small hardware producers may eventually be vilified or ignored if they don't open source their designs. Obviously this is not adafruit's intention, as they have stated many times that OSHW is not for everyone. And I think that hardware developers should take a step back and look at their own situation. There are thousands of software companies out there who don't release the source for their commercial products; otherwise, what would they sell? Hardware developers should not feel forced by the community to release that information just because it's better for the community, via sacrifice. Self preservation is an instinct and shouldn't be completely ignored.
Yet I do feel pressure from the community and have in fact received demanding requests, and had at least one person publicly warn away customers because I don't have design files available. I'm sure I'm not the only one feeling this pressure, and that's why you're seeing support in here for a non-commercial clause. There appears to be a danger that "OSHW" will become a badge like "Intel Inside", turning customers away from equally open-to-end-user alternatives merely through community parroting of the idea. Even if it's not the original intent, groups easily separate things into "good" and "bad" columns.
I think many people are casting in their support but don't necessarily agree with every part as-is. You can see explicit statements of that in the discussion pages on the OSHW wiki.100+ people do not have any problem with the open source hardware definition, you should join the OSHW community and convince them that adding a non-commercial clause makes sense.
Perhaps the community will eventually decide that OSHW just isn't the same as OSS and shouldn't be treated identically. Regardless how the matter ends, as you've mentioned several times this really isn't the place to actually influence the outcome. It's been an interesting discussion though.