I do think there's more than meets the eye in a hogging level done right, and I think GIO has actually been refining his technique over the last month or so.
It's probably best seen using the neglected Flash viewer and going up the levels:
I think as long as the Gridcosm is an open and vaguely anarchist place, one has to accept everything that happens here. I'm not saying that people should accept everything blindly and without question, but try to reframe events as necessary. You actually have no choice in the matter as long as it's a place where anyone can sign up and there are only technical rules (150x150, etc).
If it's possible to go down the familiar path of "blendy" vs "quilty" at this point, I have always been in the "blendy" camp, with some conscious rebellion against blending occasionally.
However, who's to say that the mode we are used to should stay static? Shouldn't Gridcosm evolve along with technology as well as the "norms" that we create as a community?
However, I also feel your frustration, because the argument goes that it's annoying to work on a piece diligently and carefully for an hour or more and then see it "obliterated" by a hogging level that ignores the collaborative aspect of the grid.
I think the way to get out of that mindframe is threefold:
1.) Learn how to work faster. The time spent on a single square can be well spent if you're not setting yourself up to be disappointed.
2.) Realize that although you may be disappointed to see the visual leads you have provided be ignored by a level hog, it is equally as fulfilling to blend with others and realize that nothing goes unnoticed here. People will recognize a good theme and good work when it comes up.
3.) Try some gridhogging yourself, it offers some different technical and conceptual challenges than the single square technique.
Lastly, I don't want to hold GIO up as an ideal either. I think he could work on integrating his contributions into levels a bit better and I think he could explore connecting themes with the other memebers. Currently his pieces still come off as a bit selfish and a bit like a bull in a china shop. However, I do think this is partly due to the perception of the viewer.