How is Scrooge affected when the ghost says Fezziwig has done very little to "make these silly folks so full of gratitude?"

Scrooge responds to the ghost by saying that Fezziwig deserves praise and wishing he could talk to Bob Cratchit.

When the Ghost of Christmas Past tells Scrooge that Fezziwig does not deserve praise, Scrooge refutes this idea.  He tells the ghost that Fezziwig was their employer and boss, and therefore had the ability to make their lives miserable or happy.  This was praiseworthy, to Scrooge.

“It isn't that, Spirit. He has the power to render...

Scrooge responds to the ghost by saying that Fezziwig deserves praise and wishing he could talk to Bob Cratchit.

When the Ghost of Christmas Past tells Scrooge that Fezziwig does not deserve praise, Scrooge refutes this idea.  He tells the ghost that Fezziwig was their employer and boss, and therefore had the ability to make their lives miserable or happy.  This was praiseworthy, to Scrooge.

“It isn't that, Spirit. He has the power to render us happy or unhappy; to make our service light or burdensome; a pleasure or a toil. … The happiness he gives is quite as great as if it cost a fortune.” (Stave 2)

Scrooge is said to have been talking like his former self, not his current self.  He is remembering how much he enjoyed Fezziwig’s party.  Fezziwig did not spend much.  It was not the money that mattered to young Scrooge or his friends.  What mattered was that Fezziwig cared enough about his employees to throw them a party.

Scrooge gets thoughtful and emotional when he thinks about how kind his former master was to him.  The ghost looks at him and thinks that Scrooge is affected.  He asks him what is wrong, and Scrooge says nothing is, but the ghost presses him until he admits what he is thinking about.

“No,” said Scrooge, “No. I should like to be able to say a word or two to my clerk just now! That's all.” (Stave 2)

This continues the pattern of Scrooge wanting to talk to the boy singing the carol when he sees his childhood self so solitary and sad.  Scrooge wants to talk to Bob Cratchit, his one and only employee, when he sees the difference between how his former employer treated him and the others.

The fact that Scrooge is able to rank happiness over money at this point shows that he is already transforming himself.  The visions of the past have affected him, and he is starting to think about other people than himself.  By the time Scrooge has seen the images of the present, and how he currently affects people, he will be a different man.