This Just In: Many FOSS Businesses Started by People Who Assume You Can Apply a Support Model to Any Business
Just because people hopped on the bandwagon and forgot the "plan" part of business plan doesn't mean it's a broken model, only that it's a model that can't be applied to all things.
I work for The OpenNMS Group, a commercial consulting company based around the OpenNMS network management platform. We do the "traditional" open-source business model, and it works quite well. I guarantee it won't work for everyone, but in our specific case, network management is a very large discipline that tends to need custom configuration (and sometimes even code) for most environments. Everyone's network is different, and there is no one-size-fits-all solution.
That makes it ideal for the Free Software model; you'll end up spending $50k easy on solutions from HP and their ilk, and then twice that again to get consultants to actually make it do what you want. Making the software free still leaves plenty of room to add value, help scale, and teach NOC operators how to get the most out of it without screwing hobbyists and small companies willing to put the man-hours into doing it themselves when they can't afford the budget on consulting services.
Just because someone's trying to start a company selling support for the Gimp or something doesn't mean it's a good idea, but just because the service model doesn't work for some open-source software doesn't mean it's a bad one. You still have to have a business plan, and you still have to provide value to your customers. Just because the software itself is freely available and/or Free doesn't change that. That didn't stop a bunch of companies from popping up, riding the "open source" wave...
In the end, the companies that came out with a poor strategy will fail, and others will remain, and open source will be just another boring old business strategy like all the others.