It is hard to know what crosses the line between funny and hurtful. LGBT people are at a time when they are stepping out of the shadows and changing the national dialogue on these issues. It is hurtful, rather than helpful, to make jokes about these things at a time like this. SNL actors should know better.
I think most people can agree that jokes about different groups, whether about religion, race, or gender can be funny if done properly. However, there are some people who simply cross the line without thinking of anyone else's feelings. Being careless with jokes causes undue pain, and care should be taken when telling jokes.
Whether a joke is funny or tasteful is so subjective based on so many things. Are you or a loved one or close friend a member of the group the joke is about? how insulting or innocuous is the joke. I don't think it would be fair to say that jokes aimed at the LGBT community are any more offensive than other jokes.
Granted, the LGBT community has faced plenty of persecution and unfairness, but they have become hypersensitive about jokes or remarks pushed even in their general direction. Apart from serious illness and death, no topic should be off-limits for humor and parody. That' how you know that at some point, your belief system will get to be the one delivering the punchline at somebody else's expense.