From my own personal aphorisms:
There is one overwhelmingly simple reason why bills before the Legislature should be strictly required to address only a single subject, with no non-germane amendments or riders permitted. That reason, quite plainly, is that no politician should ever be allowed to take something that you cannot live without, and tie it to something that you cannot live with. Any proposal so bad that even career politicians refuse to pass it on its own merit, does not deserve to ride the coat-tails of something that must be passed; and likewise, no bill so vital or so good that it can be defeated only by attaching a rider so bad that it cannot possibly pass so amended, deserves to be so sacrificed on the altar of gutter politics.