SO and ATT were near monopolies. But Apple's App Store isn't even the biggest mobile App Store.
This is true. One of the downfalls of both SO and ATT were that they became huge, just like Microsoft did. At least one of the issues was access and control of a market.
There are other examples: Car makers control access to vital information so that independent repair shops have trouble keeping up with dealerships. Dealerships have 1st cut to the information they need and can charge higher prices. Same with aftermarket car products, they (car makers) would invalidate warranties is someone used a non-approved product, the courts ruled against the car makers.
The size of any market, sadly, will dictate the amount of attention something gets.
In the case of Apple, I don't think it's the size of their appstore, but more the lack of access to the device. Apple has had a history of being a closed system.
My old iPod video had a very weak battery, I called the local Apple store and they wanted to test it to determine the problem then IF they determined it needed a new battery, they would charge me some $80 (IIRC) to replace it.
I bought an eBay kit for something like $10 that has been working for years. The amount of money that Apple wanted to inspect and fix the problem was more than the iPod was worth. It would have be cheaper to throw it away and buy a newer used one.
The same thing happened with PC vs Mac in the old days.
I don't think anyone sued Apple over access to the iPod or Mac as there are other products that do the same kinda thing.
However, these things have a life cycle to them. There's a difference between something that becomes an appliance and something that doesn't. Most people don't care what brand fridge they have, they care more that it works properly.
What brand name pipes carry the water to your house, most people don't know or care, they just care that it functions properly.
Would anyone care if their movie came thru fiber optics from 3M or GE or Google, or would they care that it's fast?
Do you care that someone bought an iPhone at Walmart or an Apple store? Do the iPhones from Walmart work better?
The legal aspects of this are not very clear, because people don't have to buy Apple products, but what is clear is that the appstore didn't scale at all.
The industry will change, if it hasn't started to already. Some will care that their appliance is made by Apple, but the lines will become blurred. China already has knock-offs of the iPhone/iPad for about 1/3 the price...
If BlackBerry makes a universal OS that runs on different platforms, they could change everything. They already announced a security product for all platforms. Apple's run is being challenged on several fronts, there focus has been on the product and they've been slammed more than once for not being able to make real gains there.
Consider the iPad sales, they are flat and Apple claims they are still learning the upgrade cycle. People hold on to tablets longer than phones and the phones are getting so good, they'll soon see there is little reason to upgrade.
At that point, the cycle changes, Apple (and others) will soon see that they are selling appliances not content.
Consider: which is more important to you, buying a new fridge when your old fridge still works, of buying more food when your fridge is empty?
This is why tablet sales are flat and why at some point, phones will flatten out as well. Notice how all the tech companies are looking at Asia for growth?
The whole industry will change, just like the PC vs software industry changed years ago.
