Yes, and UPS has trademarked brown (and T-mobile has purple). Remember that trademarks are limited to certain categories. If you're not competing with UPS, you can use brown etc.

I know how trademark works (I have a registered tm myself), but am suggesting that it change. To my mind trademarking 'brown' is so thoroughly uncreative. A trademark should be more than a common English word.

Trademark isn't intended to be about creativity (that's copyright), trademark is intended to be about preventing commercial confusion.

The "Pixels" thing clearly shows that trademarking common English words is ripe for confusion. A little creativity would go a long way towards reducing confusion.

You can't make DMCA request for trademarks. That was a copyright complaint that looked for a common English word. The complaint would have been overly broad whether or not it was trademarked.

Intel tried to trademark their processor model number (80386, 80486) to prevent AMD from using them. The trademark was denied and they switched to using names (Pentium instead of 80586) since then

I have heard this many times but I couldn't find a source for it. Do you have one?