But people aren't patenting lightbulb interactions, they are patenting specific manufactured implementations.
Look at it this way, there were definitely people doing pinch-to-zoom that looks absolutely identical to the way Apple is doing it from the user's point of view. Jeff Han's demo is a perfect example of it. For years, many people have been doing demos like this, but they've been doing it on big bulky setups like projected-desks, or in Han's example, using total internal reflection.
Apple just made a different implementation, using the same interaction gestures, on a capacitive screen. From a software point of view, the implementations are rather trivial and don't differ much except via how you obtain the input (e.g. capacitive, FTIR, cameras, etc) The main difference is shrinking down the whole thing so it fits on a phone.
The reason why this was possible in 2007 had nothing to do with Apple's software and everything to do with the ability to manufacture a capacitive screen that has the right sensitivity, accuracy, cost, weight, and power to fit into a phone.
Apple deserves engineering props for this. But they do not get credit for inventing pinch-to-zoom nor the capacitive screen. Both of these inventions came prior.
If Apple invents an entirely new kind of touch screen and an entirely new way of manufacturing it, you could argue they deserve a patent.
But taking what existed before, pinch-to-zoom on projection displays, and implementing it on a different screen does not deserve patent protection, anymore than taking an existing business method (e.g. 'selling flower bouquets by phone', adding the text 'via web site' or 'via mobile app') and slightly tweaking the medium in which the business is done to obtain another monopoly.
Should 'internet shopping cart' be allowed a patent when real world shopping carts already existed? It's crazy absurd.
If Apple's patent had even been more specific like "pinch to zoom, but on this particular kind of screen" I'd even have more sympathy for the argument, because at least other people could do the same thing Apple did: copy an existing idea and apply it to a new circumstance. Samsung and others could innovate by creating new types of displays, maybe using microscopic cameras to track your hands like minority report or something.
But granting a patent to Apple for pinch to zoom on any kind of screen? Sorry, it goes too far.