Well, it's true that trading private armies for a huge land wealth that could be partially spent to bribe elections and keep the rest is a better deal. However, I'm not convinced they got enough money to do so. The House of Commons was as an aggregate less powerful than the House of Lords in the 1700s, but it couldn't be ignored. Idea rarely originated from the Commons, but an Earl who made a proposal that was slightly opposed in the House of Lords but greatly favored in the commons had a good chance of passing if the Crown thought it favorable (the Crown no longer withheld royal consent from bills, but at this time it still influenced on the fence people to abstain)
In Modern Britain, a parliamentary district will have no more or less than 5% extra population compared to the average district. In the 1700s, a district could have up to 3.1 times as much as the average district. The large population districts were usually in cities. However, London still had multiple MPs.
And there is the fact that the grain prices... weren't really all that high. They were higher than before farm mechanization for sure, but no more than triple in pounds compared to the High Middle Ages. The guilds tended to make lots of money.