With regards to the commandments Old Major gives the animals, why does he see them as vices?

I think that the commandments or edicts that Old Major
forbids the animals to do are the result of how he has seen humans abuse these ideas in
their treatment of the animals.  They represent "luxuries," to a great extent, that have
been abused by humans and this reflects the disproportionate relationship with the
animals.  At the same time, Old Major points out these habits to avoid because animals,
themselves, have not been able to partake in these, representing a level of denial
between what animals do and what humans can do.  For Old Major, any replication of these
habits is a duplication of the abuse that humans heap on
animals:

And
remember also that in fighting against Man, we must not come to resemble him.  Even when
you have conquered him, do not adopt his vices.  No animal must ever live in a house, or
sleep in a bed, or wear clothes, or drink alcohol, or smoke tobacco, or touch money or
engage in trade.  All the habits of Man are
evil.

For Old Major, human
beings are seen as both a political and moral evil.  The bad acts they perpetrate are
abhorrent on both levels.  This is why Old Major sees the habits of men as "vices," and
not be duplicated.  The behaviors are vices because they are the domain of human beings,
a realm that is incapable of redemption and only likely to spur more vice and more
sinful behavior.  In this construction, Old Major has been able to give a spiritual
dimension to the animals, convincing them that what they fight for is as much an issue
of right and wrong as it is about power.