A lot of people seem to complain about this. Personally, as a user, I'm pretty okay with Facebook not showing every post from every page that I like in my news feed. If I really want to see every post from a page, I have options that are immediately available in the like dropdown of the page (either "add to interest lists", or "see first").
The thing is, in the current state of Facebook, wanting to hear everything that a page writes is an exception. As a user, I'm glad it isn't default anymore.
The problem is a combination of things. One problem is that there's pressure (from several potential sources, sometimes from Facebook's UI, sometimes social pressure from friends) to like too many pages. This has sort of diluted the meaning of a "Like" w/r/t a page.
Another big problem is that pages spam - some to the tune of several messages per day. I expect that most people who "Like" the pages that often get "Likes" (which appears to be largely big companies, bands, movies, etc.) don't actually want to see every one of these posts - they'd drown out the user's "Friends".
It is unfortunate for small business owners that things happened this way. Fortunately, really loyal fans should be more likely to listen to you when you ask them to subscribe to something outside of Facebook, or to do the extra couple clicks of adding to an interest list in Facebook. I expect, however, that some of the "loyal fan" base might be made up of (as mentioned before) people who liked the page out of social pressure.