Why 'No'? It seemed like a fair point to me. With regards to talk about suicide- I think the powers that be do probably believe (wrongly in my opinion) that talk about suicide and the acknowledgement that it might be a viable option in some circumstances- may lead to people feeling ligitamized to do it. So hence- the slippery slope...
Talk of corruption in governments is usually discouraged and potentially damaging information is usually covered up. In general- authorities probably only want SO much talked about- beyond that and they likely fear societal unrest and uprisings. Hence- also the slippery slope when it comes to questioning and even talking about our 'rulers'- obviously, some countries are more strict than others on this.
When it comes to particular phrases that move in and out of approval- I guess they accompany what is considered acceptable. Usually phrases that are now considered offensive are because they perhaps were being used offensively! Calling someone a 'retard' for example usually isn't done in a neutral way.
In some cases though, I suppose I do find that things have become very extreme because we are all so afraid of offending someone. I think the problem sometimes lies in people not really being able to read one another.
Take for example: misogyny. I've worked in many scenarios in which, groups of women have been refered to as 'girls'. It's a funny thing- because- even women will sometimes refer to their group as 'girls'. It CAN be meant as a term of endearment. However, I've also worked with men who were clearly misogynists- and- coming from them- it just feels more belittling. I doubt they'd enjoy it if we called him a boy- he's a man.
I think- especially if we don't know the person- it can be easy to misconstrue what people mean- so I think some phrases, people try to avoid. On the other hand- people can sometimes reveal their true feelings by what they say. If they say something mildly offensive- what are the chances that what they are actually thinking/feeling is even worse?!!