Modern Android phones are coming out locked just like the iPhone is. Remember, Google has shown it can and will revoke apps from your phone. So far it has done that only for fraudulent apps. So far.
No need to worry about having your warranty revoked because you want to open your phone's OS so you can use it.
See above about locked phones. If you change your phone to an unsupported configuration, you don't deserve warranty support. Producers carefully calculate warranties according to a specified set of operating criteria, and to ask them to support other criteria is unfair. I wouldn't expect Ford to honor the warranty on a custom stroked, bored and blown Mustang engine either.
No threat (since removed) of being sued because you dared unlock your phone so you could DO what YOU wanted to do.
No, they just threaten to sue all the sources of the complete Android OS that you can download from. Instead, you can legally get a substandard Android, stripped of most of the standard apps that it's known for. Oh yes, not all of Android is free, just the basic core system. All those cool apps that come with it are Google proprietary, the custom carrier user interfaces are carrier proprietary.
In fact, you have the source code to the OS - you can change the kernel, write and distribute applications and extensions as you desire.
Quite true, but that's a geek thing. It doesn't apply to the vast majority of buyers.
Likewise Apple. However, Google only does that for apps in the Android Market; the other marketplaces, Google cannot touch.
Given that Android shipments are outstripping the iPhone, I think the majority of buyers are fine with Android. It's taking over the market, already having a larger marketshare than iOS, and extending that lead.