Because capitalism is built on a series of MUTUALLY BENEFICIAL transactions. So when I buy a product - I gain something because I now have the product and the company gains because they've sold me that product presumably at a profit. The reason I buy something is because buying it makes me better off.

I like things that make me better off - therefore it is perfectly reasonable to like companies - esp ones that make important/complex things that I derive a lot of benefit from.

That's a pretty neat question. It's not "Why would anyone like a company," but "Why would anyone want to like a company". An example of why one might want to like a company is for when he or she is buying stock. One doesn't have to like the company, but it can influence the decision of buying if one doesn't like the company. I'm not saying that I would never buy stock for a company I don't like, but the decision of spending my money comes much easier if I like the company. However, there are flaws with that argument seeing as my liking the company could potentially cause me to over-invest and lost my money because I thought I would buy stock for the company I liked. There are pros to why someone would like a company; however, like in the example I showed above, there are equal cons. But if you own the company. I see reason to want to like it =]

Why would anyone want to like a brand, a product, an ideal, a religion, a soccer team?

Why would anyone want to dislike a company? Why would anyone want to dislike anything at all?

I suppose it's to avoid the conflict between short-term personal gain (X is making a good product) and the more general long-term global loss (X actions go against my personal principles; X makes the world a worse place to live).

because they make (for the most part) nice stuff.