Note: I call them "company name tags" here, and use "company tags" to refer to the bad ones.
It's simple, we can just follow the rules from
The Death of Meta Tags
to decide which company name tags we keep and which company name tags we get rid off.
The rules of the above blog post are simple:
If the tag can’t work as the only tag on a question, it’s probably a meta-tag.
If the tag commonly means different things to different people, it’s probably a meta-tag.
Although these rules are specifically tailored to tags like best-practices we can tailor them to be rules about company name tags. Here's my take on it:
If the tag can't work as the only tag on a question, it's probably a company tag.
If the tag covers different products, it's probably a company tag.
Tags that are just about the company, are company tags, and aren't welcome.
We have two kind of company name tags, those that surely cover multiple products (eg. apple) and those that almost cover single products (eg. western-digital) in the computers field.
The former are deemed company tags, simply because you can't ask a question about just Apple (rule 1) on Super User as it would be off-topic, the tag also covers a lot of products so it's more kind of a "group tag" than it is an "useful tag", similarly as to how best-practices grouped tips. Hence, this company tag is of no use and should go; if you don't believe me, read Daniel Beck's detailed answer...
The latter are rather useful, a question about Western Digital is most likely going to be a question about their hard disks or something closely related (RMA, firmware, ...) and it covers just a bit more than a single line of products, but nothing close as to the very wide branch of products Apple covers.
Western Digital hard-drive users surely will love a tag for that matter; however, I don't see how an incomplete Apple tag is going to be helpful in any way, as there's always a more specific and more complete tag to follow like macbook, and so on...
The Death of Company Tags
So, can we get rid of these company tags that just group other product (group) tags together?
For some tag it might be of a benifit to split them up into more specific tags, like razer-mouse, ... instead of razer.