You're right that they're not good business tools, but Jobs and his teams were ridiculously focused on consumers-- the end purchasers.
I'm not an Apple fanboi, and far from it, but a lot of dogged work produced a clear and early market leader that sustained its leadership-- if by monopolizing its ecosystem.
Much as I'd like to see Apple open up, I believe the DoJ (in this segment) has a very flawed argument. Google isn't a hardware company, for one. Microsoft doesn't know hardware (Balmer totally blew the Nokia acquisition), either, and is still worse at supply chain. Lenovo's purchase of Moto phones remains one of the better alternatives.
Is the barrier to entry really high? Yes. But just like there are new and bothersome competitors to Tesla coming from China, Apple will have to work hard to maintain their throne-- they've been greedy and control freaks to the max to their developer monetizing networks. If nothing else, Jobs taught the market how to do phones, did it, and left competition in the dust. This said, I use an Android phone. It's not inferior to Apple, but my phone vendor could give a flying fuck about me.
Ultimately, apps rule this space and Apple controls its ecosystem with draconian and maniacal care. You'll have to pry their fingers away, one by one, to get control. Citing the stupidity of Microsoft/Nokia, LG, and others is not going to convince a judge.