There's a distinct difference between constructive criticism and unnecessarily nasty comments. I'm not for a moment suggesting that personal digs or bullying behaviour are an inherent part of blogging or something that we need to get used to, but I do believe that a certain level of content-related critique can be extremely beneficial. In the same way that the blogging community (quite rightly) stand up against cruel personal jibes, I've seen an increasing trend for bloggers taking every comment not entirely in support of their content as unacceptable, when sometimes its message can be turned into something really helpful.
I definitely buy into the 'create content you'd like to read yourself' method of blogging. I blog about anything and everything that takes my fancy, believing that there's nothing wrong with combining posts on a whole bunch of different topics in one place. Like everyone, I sometimes get wicked feedback from posts; sometimes not so much. It goes without saying that many personal or petty comments on a post aren't even deserving of a second glance, but the ones that offer genuine critique and opinion are often well worth listening to. I feel as though no matter how much you're dedicated to the idea of blogging for yourself, it's always important to keep the thoughts and opinions of the people that take the time to read, comment and interact with the content you produce at the forefront of your mind, too. The level of support I receive from readers is often overwhelming and inspires me to produce content that others will enjoy reading as much as I do creating.
Although I'm sure that the level of blogging criticism received is different for everyone, I think it's important to remember that not everything is a personal attack. Some points made can actually be super beneficial to both the blogger themselves and their readers. For instance, comments on the length of my YouTube videos and the lighting used in photographs have really helped me to understand how to improve my content in the past. I identify myself as a blog reader above a blog creator, so I see it as really important that the blogs I read take the thoughts and opinions of those that have followed them for so long into account, at least every once in a while.