I can appreciate your point that the term "open source" can be confusing, but given that there are 58 different open source licenses approved by the OSI (and that doesn't include licenses that are used for practical applications such as MySQL and BerkeleyDB), I don't really think it's fair to say that we're misleading people. It's inherently a poorly-defined term.
There was already a free version of Lampshade for personal use before, but the source was closed. Now, it's open, which is why we're calling it open source. We're not the first company to ask people to pay for commercial use, and I doubt we'll be the last.
Hope this clears things up.