These assaults are absolutely not new, but from my limited vantage point, previous assaults have mostly revolved around vulgarity. The new wave seems to revolve around "hate", which is worrisome given how subjective and slippery the term is. The described tale of "Zombie Muhammed" is a perfect example: a light-hearted joke to one person is a vicious act of "hate" to another.

Protecting people's feelings should not be the role of the state.

I don't think that category is that new either, though it's hard to say if it's increasing in frequency. One very traditional category is desecration of cherished symbols: blasphemy laws are one very old example (still extant in some of Europe), and the U.S. has had recurring debates over whether flag burning should be outlawed, which it actually was for a time (basically the patriotic American's version of calling for Koran-burning to be outlawed).

I do think it's true that, at least since the 1960s or so, the U.S. has supported a basically unlimited range of political opinion (excluding the flag-burning issue). Perhaps something of a historical anomaly, though, since even in the U.S. that was generally not true earlier: between various sedition acts, laws suppressing communist and anarchist publications, laws suppressing anti-segregationist speech, etc., there have been significant restrictions on "fringe" speech through much of US history.