Swift was criticized for the ideas satirized in Gulliver's Travels because he found fault with English political parties.
The novel by Swift is itself highly critical of the English customs and government, country's religious struggle and so forth.
For instance, the two main parties in England, the Tories and Whigs are satirized by Tramecksans and Slamecksans of Lilliput. As the Slamecksans wear low heels and the Tramecksans wear high heels on their shoes, which makes them seem ridiculous and Swift criticizes King George II for his sympathy for a style of shoe.
In addition, it satirizes the divide between Catholics and Protestants, the Big Endians believed the egg should be cracked from the wider end whereas, the little Endians believed eggs should be cracked from the smaller end.
In highlighting the difference between Catholics and the protestants Swift makes the disagreement over religion seem ridiculous.