By the same token, a gradual increase in the legal and customary respect shown to animals could inculcate a growing respect for our fellow humans.
I'd summarize my position as: 1) animal interests for their own sake are not a legitimate end of government coercion, and 2) the moral character of the people is a legitimate end, but we should be very hesitant to use coercion for social engineering.
d) animals suffer, we should care, but we should not pass laws when their sole purpose is to prevent that suffering.
There is more to a society that what it compels at gunpoint. We can abhor behavior without proscribing it by law.
What space for different conceptions of the good, for diversity of values and preferences, could exist in such a society?
You must have limiting principles for when we should resort to the remedy of the law. Perhaps yours are different than mine, but I doubt that you have none at all.