What are the purpose of these anonymous guests on the forum?
A forum can accept guests' replies on topics. I have seen it on other forums too, just for privacy reasons. Bitcointalk has probably removed this feature because of spamming. Although, I think that being
Anonymous is different than simply being
Guest.
The profile is not click able, so meaning the guests aren't trustable as I may think, right?
It doesn't have to do with trust. They're just guests. What exactly do you want to know about him? He has never registered, he has no rank and you can't know how many posts he has made, because he want to be private.
I have a feeling that the option to activate to anonymous profile had been terminated, or something, I'm a right?
Yes, you can't do that anymore. (thankfully)