Why? OS/2
IS great already!

Question is: If you ask 100 people in your town: "What is OS/2?", I guarantee 90% won't know.
The typical thing like back in the days, when OS/2 was still maintained by IBM: People don't know the product, and/or don't know what it is for.. and why they should give it a try, even though they have Windows running. :>
As for ArcaOS: As soon as the typical problems are gone (browser, usb, uefi, gpt, localisation), merchandise should start, so more people actually know the product. - Perhaps even a demo live CD. (Perhaps not like AOL-CDs which were EVERYWHERE xD). - I often see people interested, but they are not willing to spend 117 EUR just to try out a product.
Anyway.. getting offtopic a little bit, I think I could prove OS/2 is not well known enough to be compared with brands like Mc Donalds or KFC.
But still, as Guzzi said, there still is Copyright. And since IBM and Microsoft have their hands on that stuff, this might be a thread for these two (and their lawyers). I suspect goodwill is required to officially abandon the brand and hand it over to somebody else. You might not be able to fight for this at court, as these companies have the ressources and also the best lawsuits in the world..
And even though the brand is gone, world wide, it's still "glowing hot iron".. better not touch it. ; )