I was speaking with colleagues, and their argument was: the XBox, the PS, all these things are closed systems and so it's OK for the iPhone to be closed too.
But I disagree and I've stumbled on the argument why: it's all a question of "what software" the system runs, and "the capabilities" of the system.
The best analogy is the old 8 bit Nintendo and Segas.
1) for "capabilities" this was very specifically designed hardware, with only one goal which was to play games. It couldn't really do anything else.
2) for "what software", these systems ran in-house designed specific software, again just for running games
Today, we have the xbox, Play station, ipad, iphone:
1) for "capabilities", they are pretty much computers, point in hand: they have CPUs, hard-disks, disk-reader, graphic cards,
2) for "what software", I am not an expert on gaming consoles, but Apple basically uses a re-written version of Unix (BSD) for it's OS.
Basically, where I am getting to is, I think none of these systems should be closed, and we should have "root" or "root-like" access to all of them. Imagine you buy a PC from Dell.com and you don't have Admin rights.
Now, the question of the warranty remains, and I accept that vendors can decide that your warranty is void if you use your root access.
But that's OK with me. What's not OK is not having the choice and being forbidden from having this choice.