Because there is a bigger picture here than just "buy a different phone" as mobile computing becomes more ubiquitous. I think that having a single app store on the dominant platform that everyone is forced to go through is akin to having a single browser on the dominant OS. So in the end it's not about suing Apple per se but if a suit against Apple were successful then the rest of the market players would be forced to open up as well.
I think it would be pretty easy for Apple to allow apps to be installed on their devices without having to go through the app store. You can already jailbreak to do this so the capability is there Apple just needs to allow it. Not sure what legal damage you think they would incur except whatever they would pay to fight the suit.
The legal damage would be the fact that each design decision they made around the store would be under court scrutiny.
But so far, you haven't explained why this should be done given that Android offers what you ask for. What's wrong with letting people decide for themselves?
Android is more open in the sense that there is more than one market and anyone can build a marketplace for apps. Yes, there are places where Google is not open with Android as well but my main problem is there is only one app store for iDevices. My thinking is that if Apple is forced to open up in terms of allowing more than one channel to sell apps through, or to sell directly, that it won't cede the market to Google but will set a precedent for all players.
It sounds like you are saying that you want Apple to be forced to do what Google has already done. Doesn't this mean the the precedent has already been set but Google?
That leads back to the original question: Why is it so important for Apple to be forced to operate like Android when people are free to just buy an Android phone if they want that kind of environment?
Yes, that is what I am saying. Google has set a precedent but not a legal one. So leading back to the question there seems to me to possibly be a case that Apple has a monopoly of sorts and that it is not allowing proper competition because of the power they hold to arbitrarily delete a developer's app without recourse. I don't know if the argument would hold up in court of course and it's certainly not a straightforward argument for reasons you have pointed out, namely people can switch to Android, but I think it should be tried. As for what is wrong with Android - nothing really. I don't use it as I prefer the iDevices so far but if Android does at some point become dominant then what is to say they won't try and close off the market in a similar fashion?
I do now understand what you mean as far as a legal precedent is concerned, but if a ruling were based on the idea that Apple had a monopoly then by definition it wouldn't apply to anyone else.
[edit: removed point about Apple not having a monopoly]
When I see comments like the parent's the logic seems to be: "Android isn't properly open, so let's sue Apple."