For me the difference between a 3x3 knockoff and a V-7 knockoff is in respect towards the official company.
I respect Rubik for inventing the original 3x3 mechanism, but this was decades ago and the patent has expired. He and Seventowns have already made many millions of dollars from this and I don't think they need more money any more than I need more air. I don't respect Seventowns as far as helping out or supporting the cubing community, because they really haven't put a lot of effort into trying to make their cubes better. As far as I can tell they think we are "fans" of the company itself. So I don't really mind if a few knockoff cubes are sold, especially if they are better than official storebought cubes, which in my opinion they certainly are.
On the other side, we have V-cubes. Verdes invented the mechanism and has patents which still apply. As a small business owner rather than a large corporation, the money from buying a cube really does affect him and his family. And in addition he helps out and supports the cubing community: V-cubes tries to improve their cubes however they can, is working on coming out with the remaining cubes, agreed to produce cubes in both white and black plastic, and has made friends with quite a few of the fastest bigcube solvers. I really do respect Verdes for this and that's the main reason why it saddens me so much more to see a knockoff V-7 than to see a knockoff Rubik's cube.
About trademarks and DIYs: I have heard that the Rubik company has trademarked the 'image' of the Rubik's cube. So this means their intellectual property is of a cube with 9 stickers on each of the 6 sides, and the color scheme on black plastic. However, even if this is true, unassembled DIYs do not fall under this trademark! Nobody is going to buy a package of cube parts and sticker sheets and think it is an official Rubik's cube. It may look like a Rubik's cube once it is assembled, but if it is not sold that way the trademark does not affect it. As far as the mechanism, the patent for that is expired, so there is no problem with that.