i think there should be a complexity requirement to the invention. sure you can describe a modular power supply in a paragraph, but it will most likely be bloated to make it seemingly more complex. they should crack down on this.
a natural progression also should not count as an idea. like the nail claw on the back of the hammer. it used to be you had to have a crowbar to pull messed up nails as well as a separate hammer which was essentially double headed. surely a bunch of different blacksmiths all over the place got the idea at the same time, and started making hammers with a nail claw in the ass end. that would be something patent worthy perhaps, so its not the best example. duct tape inventions, in which two gadgets are merged into a single gadget that has the functions of both, should not count.
i also think that you must have a working prototype to show that the idea isn't completely bogus. in theory patents should not be allowed. if you want an invention to make you the inventor money, then you are gonna need to market it to corporations or take out a loan and start your own business. if you want inventor to be a job title, it better be work you're doing. people see inventions as a get rich quick scheme. they think if the come up with a simple device they can make millions for at most what amounts to a couple years work.