Well, benefits and baggage. While fixed format publications are a pain on smaller devices, they do have some benefits. One of the biggest benefits is quality control and another one is cost. The direct translation of a magazine from print to electrons ensures that the consumer gets something that looks great without the added cost of producing separate publications.

Another reason is to avoid reinventing the wheel, because reinvention means that you will end up rediscovering a lot of things that didn't work and were discarded. Put another way: we know how to do print. We spent about a decade figuring out how to do web pages. Do we really want to go through that process again?