First time for everything. When GOG announced these upgrades they also said this was the first step toward their publisher efforts. It sounds like they’re starting up a publishing arm using these games as their first release. So in that context, yes it makes sense that they would release these on other platforms.

The showcase even stated that GOG worked with modders and other developers to get this work done. Plus, GOG had been doing this type of work for a while now with their preservation program.