While I think it's unreasonable that obviously hardware aspects aren't covered by some manufacturers after rooting, is there a straightforward better alternative? I'm honestly wondering, because I wouldn't expect a company to provide support for a device with software they didn't authorize and aren't familiar with. If you want a device that you own, then you need to be responsible for the full cost of ownership, though again that should ideally only extend to software and aspects of hardware controlled by software.
Personally, I don't have a need to root or install alternative ROMs until well after the warranty expires on my devices, so I don't mind the current situation as much as some.
It doesn't void your warranty, although the manufacturers have done a very good job spreading that lie. It is illegal in the US to void a hardware warranty because the user altered the software. If they can prove that your alteration led directly to damage, then they can refuse to cover that specific damage, but that's all.
