If everybody stayed home when the weather looked bad, and never took any risks, then there wouldn't be any accidents and MRT's would have nothing to do.
Mountain weather is, as has already been pointed out, fickle. If you go out after a bad weather warning and happen to get caught, then the consequences arise from a combination of optimism and bad luck, not stupidity. And if people don't even bother to check the forecasts first, then that's down to ignorance, again not stupidity.
Whilst I can sympathise with those MRT members who were called out in such terrible conditions to save those people, at the same time I have to say - that's their job. I would imagine that very few people set off with the intention of inconveniencing or endangering the MRT. So I do think it's rather out of order for them to be critical if they do get called out.
As you say, if you don't take some risks with the weather, you'd be stuck at home most of the time. But you need to accept that if you take these risks then chances are you'll occasionally get caught out.