I think it made for a very strong and touching point when Nadella said they want technology to bring the best of people, not the worst. So they were able to use it in a way, even if it didn't go exactly as planned.

I don't think so, at least, not exactly. I suspect that Tay is more designed to help with NLP, and specifically to improve the understanding of how younger generations are speaking and writing, and to more quickly adapt to changes in languages.

I do think that Microsoft will continue experimenting with Tay (and other bots) and will use the data to enhance both Cortana and their other ML services, which would obviously benefit this bot framework.