I'm not sure if the standards are low, rather that the examiners don't abide by the rules set out by the USPTO. Novel and non-obvious are both requirements.

because the meaning of a patent’s claims are often not clear until after they have been litigated

This is another failing of current examiners. The patent should be written such that one skilled in the art could reproduce it. The patents are convoluted and unclear enough that one likely couldn't produce much of what is patented, because its not clear what the invention is. The examiners should make people resubmit patents, under time constraints, so that they are clear. Much like submitting to a journal.