Of course the Toyota dealer says that, they want you to buy it from them so they can make more cash. I got my oil changed at a shop which wasn't a Toyota dealer and they replaced the filter at 16k. The FRAM filter they used had more pleats in it than OEM and appeared to be made from a similarily fine filter element.
On a side note: I love how some of you on here are "Toyota filter, Toyota Fluid, Toyota, Toyota, Toyota". You guys do know that Toyota doesn't make filters, fluids, wiper blades, tires, etc. You are actually better off going aftermarket on some things. For instance, Toyota's wiper blades, fliters, tires and batteries are made by someone else anyways. Those same companies that make the OEM stuff make the aftermarket stuff and most of the time the aftermarket stuff is higher quality than the OEM stuff because Toyota wants cheaper (inferior quality) stuff when it comes to those items than the autoparts stores and tire shops would sell. As for fluids, even Toyota admits in their manual that while Toyota OEM fluids are always right for your car, aftermarket fluids that have the same characteristics are not only acceptable but they interchangable.
As long as the aftermarket fluids, tires, batteries, etc are higher quality than OEM (which most mid line aftermarket stuff is: Tires are a perfect example, Toyota puts crappy Integrities on the Corolla as OEM but Goodyear makes a better tire for the Corolla like a TripleTred.) Then you are fine using the aftermarket stuff. I'm an OEM freak, and I required the body shop to use OEM fluids when they repaired my car, but that was because I knew if i didn't specify OEM that they would put cheap coolant in the car. As long as you are doing the work and know the stuff is of better quality, then don't pay any attention to the fact it didn't come in a Toyota box.
TRD = Toyota Racing Development. MAF = Mass Air Flow, as in MAF sensor. You by no means have to use OE. But I always do while the car is under warranty. Some dealerships will refuse warranty work if you do not use OE, and have it installed on their premises.
A dealer can't legally do that, and Toyota would hate to hear that they did. A dealer can only deny warranty work if they can prove to Toyota that the non-OEM part caused a failure that you want the warranty to cover. It even states in your warranty document that while they recommend using Toyota parts for repairs, using aftermarket parts will not affect your warranty unless those parts cause a otherwise covered failure.
If a dealer ever tries to say, I'm not covering your car under warranty because you didn't use a Toyota filter, wiper, etc. Call Toyota Corporate, complain loudly. Make sure they understand that the dealer told you they wouldn't work on your under warranty car because you didn't have them install a OEM filter or whatever. Then take it to another dealer who will honor Toyota's warranty. If Toyota cares as much about the customer as they say then they will repremand the dealer and possibly pull their agreement if this is a recurring incident. Ford has revoked their agreements with several dealerships for the very act of refusing to repair under warranty cars that were under warranty because they had some Non-OEM parts on them. Toyota would probably do this as well.