I have a feeling that many of the fans who chanted don't necessarily want Dalglish as manager, but he is a figurehead who can be seen as the "anti Roy" in that he wanted the job in the summer, he is at the club now, he could do a short term job for us.
If fans started chanting for the manager they really want then you could end up with 10 different names being sung at once which would sound ridiculous. By chanting Dalglish then it unifies everyone in their desire to remove the current manager and replace him with someone who they feel would be better suited. It is also a good alternative to "Hodgson out" which I am sure many fans are scared to chant for fear of being labelled by the press. Even though its what they all want, its not the Liverpool way to demand the managers head. Chanting Dalglish is probably the next best thing to this though.