I loved my MIL with all my heart, and she was bedridden and blind for all the time that I was privileged to know her. She was a wonderful, loving mother, who raised a wonderful, loving son, and that is all the reason I ever needed to love and appreciate her, though there were a myriad of other reasons, as well. Fortunately for my hubby, he could say the same thing about HIS MIL (who was thankfully neither bedridden nor blind, but just a loving, wonderful mother).
MIL jokes are just that – jokes. There are some selfish and mean-spirited women in the world, and that nastiness is clear before they ever become a MIL. No one should tar all mothers-in-law with the same brush.