or allow people to subscribe via their web browser in their ipad. ...
Apple needs to start opening up their products like ipad, iphone, ipod and Apple TV to allow third party software that is great. and stop protecting their turn in a monopolistic manner!!!
But (unless I'm missing something) you've pretty much pointed out exactly why this isn't a monopoly at all. A magazine publisher could just as easily make an ipad-specialized web version of their magazine that requires a paid subscription, and then people on their ipads could pay for it and see it on their ipads by using safari and it would basically be exactly the same as if they bought the magazine's ipad app. Or as other people suggested they can put their magazine's free app in the apple store and then handle paid subscription content on their own just as easily.