Look at the EFF's example. Say it's 1987, you've been playing with AOL for a bit, and you realize that someone might want to use a computer to do stuff like ordering pizza deliveries. You file a patent where your "invention" is "okay it's like pizza ordering on the phone but you do it with a computer instead." Then you pass it through a lawyer who draws up some diagrams to make it look like it's an invention, and boom, patent US4797818A is granted and you now control the entire online food delivery ecosystem until 2007. Oh, but then someone else says "wait, what if the customer does that but USES A PHONE." Well, now they own that for 20 years, so now you both can arbitrarily limit this space. Great. Oh, but now swomeone says "oh, but what if you do this and also the food is displayed IN CATEGORIES!" Well now he's got a patent, too.
It's madness. The problem isn't that it's too cheap to acquire and maintain these. The problem is that these are so obvious that they are no longer inventions.