I am a firm believer in open source, with the caveat that authors should always and everywhere have ultimate say over how to release their own work, never legislators or courts. FOSS may be the morally and technically preferable choice for many projects but is not inherently superior, and there are several advantages to going proprietary - plenty of examples where paid software is actually higher quality, regardless of whether it is developed in the open. This is also likely to be the case with ML software. If you want nice things then pay for them, but ultimately authors should be able to retain full creative freedom and executive control over their own software and let the marketplace decide.