Why did Pip not enjoy the Christmas dinner in Great Expectations by Charles Dickens?

The Christmas dinner is described in Chapter 4 of Great Expectations. Pip does not enjoy it because all of the adults, with the exception of the kindly Joe Gargary, make derogatory comments about him. He tells the reader:

But they wouldn't leave me alone. They seemed to think the opportunity lost, if they failed to point the conversation at me, every now and then, and stick the point into me. 

Unfortunately, there are many adults who make mealtimes unpleasant for children by using these occasions to instruct them on good table manners and other aspects of deportment. The fact that Pip's sister permits and encourages this at the Christmas dinner characterizes her as a woman who aspires to social advancement. This will explain why she attaches so much importance to the fact that Pip has the opportunity to become acquainted with the wealthy Miss Havisham and her adopted daughter Estella. It also explains why Pip's sister is so unhappy about being married to a humble working man like Joe Gargary.
The following excerpts from the dinner-table conversation are examples of the way Pip's sister and her guests displayed their own bad manners by "sticking the points" of their moralizing into Pip.

My sister fixed me with her eye, and said, in a low reproachful voice, “Do you hear that? Be grateful.”


“Especially,” said Mr. Pumblechook, “be grateful, boy, to them which brought you up by hand.”


Mrs. Hubble shook her head, and contemplating me with a mournful presentiment that I should come to no good, asked, “Why is it that the young are never grateful?” 

In addition to suffering under the disapproving scrutiny of all the adults except his good friend Joe, Pip is not delighted with his dinner because his sister serves him the meanest portions.

I was regaled with the scaly tips of the drumsticks of the fowls, and with those obscure corners of pork of which the pig, when living, had had the least reason to be vain. 

Pip also has a guilty conscience because he stole so many things from his sister's larder to give to the convict, as described in Chapter 3, and stole a file from Joe for the same purpose. The poor boy is living in dread of the moment when his sister will discover the pork pie is missing.
It is no wonder that Pip is shy, sensitive, inhibited, and solitary, considering the kind of environment he has to grow up in. He is fortunate to have one good friend in Joe Gargary. Although Joe cannot protect Pip from all the cruel digs he receives during this unhappy Christmas meal, Joe does his best to soften them.

Joe's station and influence were something feebler (if possible) when there was company, than when there was none. But he always aided and comforted me when he could, in some way of his own, and he always did so at dinnertime by giving me gravy, if there were any. There being plenty of gravy to-day, Joe spooned into my plate, at this point, about half a pint.