I have some thoughts on both sides of this issue.

First, I'll give you the 'no pets' argument...
A friend of mine has some very extreme views on many subjects including that of pet-keeping. Her argument is that a pet is basically a slave to its owner.

While I do find her point over-the-top in its validity, I do think it has some things to think about. If you are keeping an animal in a cage (except for some very useful purpose - i.e. farming or conservation reasons), you are depriving them of their natural habitat.

For this reason, I really do hate many pet stores because they encourage animal collecting - I have to have such-and-such because its trendy, not because I want and understand the animal.

For me, a caged animal is no longer an option unless it fills those other requirements. (I will be keeping fish soon so that I can use them in aquaponics - i.e. to help me grow vegetables to eat.)

Saying that, there are plenty of people who cannot keep a dog or a cat due to apartment living, so fish, birds and rodents become their main options. In those cases, I would recommend having something that can be cuddled and appreciated outside of their cages. (My son had a rescued pet mouse at one point - he did love that thing and would carry it around with him in his pocket. The subsequent hamsters were nowhere near as friendly.)

The pro-pet arguments are many...
Teaching responsibility - for (supervised) children.
Lowered blood pressure in those who have a cuddly something to sit on their laps or whatever.
Giving a rescue animal a needed home and love.
Teaching/fostering unconditional love...

I think the reasons are many - I just don't want to see animals "collected" in order to be kept in cages... Neither do I like to see farm animals in pajamas or other ridiculous notions - again, there are reasons (i.e. a hairless animal or one who has had something happen to require assistance) but by and large a pet's natural fur/feather/whatever is more than adequate to cope with most of our conditions - and is actually hampered by adding fake coverings!

Sorry so long - I'm a writer, can't you see??? I almost decided to make this into its own post, in fact - may yet do... but not today.
(I have a fiction series you might like to check out when you get a chance.)