I don't think that IBM had much choice in the marketing department The only way to effectively market an OS is to be in the OEM channels. Unfortunately, rumour has it, Microsoft made it very difficult for an OS vendor to access OEM channels.
People and businesses wanted DOS/Windows, and that meant shipping DOS/Windows on most of their machines. Vendors simply could not dump those operating systems. It would have been nice if they could have marketed OS/2 on separate models, but (rumour has it) Microsoft had OEMs paying for DOS/Windows by the number of machines shipped. That meant that you would be paying for DOS/Windows on top of OS/2. In a price conscious market, that is a no-go.
I kinda wonder how many OS/2 installations are still out there. While IBM may have had trouble getting those installations, many of them were lasting. I know my bank was using OS/2 until a year or two ago. Well after IBM formally dropped support.
IMHO, OS/2 updates were fantastic. A pain to apply, but they were issuing comprehensive updates long before Apple or Microsoft were. Those updates not only fixed bugs, but they also updated the API. IBM didn't choose to ram-rod upgrades down users throats like Microsoft and Apple does. I think that's admirable: good for ISVs and good for the end user.