Squire Cass is a contender for the narrator's Least Favorite Character. Sure, Dunstan is bad—but look at who he's got for a dad. He's bad-tempered, neglectful, slovenly, and arrogant. The only possible good thing about him is that he has the "self-possession and authoritativeness" (1.9.1) that some of his neighbors lack. He enjoys throwing his annual New Year's Eve party not because he likes company but because he likes showing off and performing his "hereditary duty of being noisily jovial and patronizing" (1.12.30).
You have to feel a little sorry for Squire Cass, though, because his reign of triumph is coming to an end. The only reason he thinks highly of himself is that his society is so confined that he's just never been around anyone superior. He may be at the top of Raveloe society, but, as England becomes unified as a nation, isolated pockets like Raveloe will no longer exist. It'll be impossible for a country squire to go on thinking that he's better than everyone else, because railroads and newspapers and other forms of mass communication and mass culture will introduce him, however unwilling, to a larger world.
Added to that, the Napoleonic Wars are almost over. Silas Marner is set sometime in the early 1800s, before the Battle of Waterloo in 1815 puts an end to the wars that England had been fighting on-and-off in Europe since 1793. The war, since it kept foreign grain out of England, raised prices for agricultural products, meaning that farmers like Squire Cass (and the villagers) could make a good living. When the wars ended, prices fell, and even restrictive import laws didn't help for long. By the middle of the 19th century (when Silas Marner was written), England was a manufacturing nation. Wealth lay in the cities, not in the lands.