Well, one reason not to is limited hardware. In an embedded system where memory is at a premium and you may have serious constraints on how long things take (e

Well, one reason not to is limited hardware. In an embedded system where memory is at a premium and you may have serious constraints on how long things take (e.g. for timing purposes), the ability to hard-code an address or have it entered in some way saves you from having to support an entire DNS layer in that system.