Isn't the Linux/GNU philosophy "Use the best tool for the job". Making OSS always a choice is good, but it is definitely not always the best tool for the job.
With proper funding you can hope open-source will become better and hopefully if more actors join the cost might even become lower.
Of-course you can continue to enrich the likes of Microsoft today because they are "better" but even not considering the cost with the current trends in Microsoft (and others) products you might still end-up with something worse and another expensive bill to pay to try to leave ...
Every one of those will have someone arguing that it should determine “best” status. A compromise like “usable and we have more control” seems quite defensible.
Either way, you can't make a rule for people to choose the best tool for the job. A rule like this may come closer to the GNU Linux philosophy.