Hazir, I get what you're saying but two responses:
1. If you're trying to make a point to make people who agree with you feel better, sure that might be a good approach. But I would assume that any action is actually targeted at the coreligionists of those who are committing violence in Muhammad's name. Perhaps the theory is that a confrontational approach will convince them they cannot solve this issue with violence, but I think that's silly - it's likely to just make said coreligionists more sympathetic to those advocating violence. So it seems counterproductive.
2. On a less practical level, I think that there is frankly no reason to intentionally antagonize someone else and insult their beliefs if said beliefs are fundamentally harmless. And while we both probably agree that there are a lot of religious beliefs that are far from harmless, a choice not to create visual representations of one's prophet doesn't seem all that problematic. That doesn't mean that all depictions of Muhammad should be off limits to others - that is indeed restrictive. But it does mean that someone choosing to not only actively antagonize but do so in the most insulting way possible... well, such behavior is legal but regrettable. It should not be lauded or copied just to make a point.
I frankly don't think this is such a religious issue. There are other symbols - national, ethnic, or otherwise - that also engender very intense feelings in certain communities. (Think a Confederate battle flag in much of the US, or the Union Jack in a Republican stronghold in NI during the Troubles.) Is it unreasonable to suggest that one should attempt to be sensitive to these feelings assuming there is no substantial harm in doing so?