We laughingly refer to cold air intakes (CAI) as "hot air intakes" as it takes hotter engine compartment air, rather than ram air from the factory air-to-air intercooler design. The factory design is actually very clever and blocks almost all the hot air from entering. A CAI sounds louder so it SOUNDS like quicker throttle response, but isn't really. Even if it did increase horsepower by 5%, that is virtually indiscernible to humans, aside from the "seat-of-the-pants" dyno.
On the other hand, we do lots of stuff to our trucks because it: a) looks cool, or b) sounds cool, or c) simply because we can.
If the sound is a bit too much (and it was for me when I tried it years ago) the filter still fits inside the factory airbox without any modification. It gives you about half the increase in intake sound, especially at full throttle, and the straight intake pipe, but also runs cooler air from the factory airbox. I also like the cleaner look with the factory airbox. It looks less "home made" to me.
Others have used the factory airbox cover and cut away the insides, but that defeats the very good factory design that uses cool air above the washer fluid reservoir, to cool air going in to the intake. It is essentially an air-to-air intercooler.
As for filters, I am from the school that says the very slight amount of extra very-fine dust ingested by the engine is easily absorbed and has zero effect on longevity. Lots of people have done panicked tests showing how much extra dust enters the engine or how much less microns or microbes or megamicrorobots K&N filters can filter out, but no one has come out and said what I say, "So what?"
It doesn't hurt anything when it is such a tiny amount going into a great big engine that sucks in a whole LOT of air. Besides, that's what oil is for. The old: cools, cleans, lubricates, protects, from my flying days.
If people never modified their vehicles to suit their taste and just came on this forum to complain or to ask questions about what is wrong with their vehicle and never get answers ... well, we would all be on that OTHER forum, wouldn't we.