I was somewhat surprised that IRIS Analytics was not required at all since there
was no Cube nor Pivot nor Dashboard. I built it myself just using dc.dc.bi.PopSongs.

Yes, IRIS contains IRIS BI for analytics but it needs additional skills to know it. 

We want IRIS users to be able to create analytics solutions if they know PowerBI, Tableau, and Logi and use it vs the data in InterSystems IRIS

I understand them - they indeed provide the cloud infrastructure to host the development and to build and deploy containers then. Somebody pays for all this pleasure.

Nobody prevents from setting up the personal infrastructure similar to CodeSpaces even now. I don't see very much need for myself yet - my mac laptop is enough productive with VSCode and Docker desktop installed.

Though I agree on the power of generators and projections IMHO it significantly raises the complexity of solutions. And I'm not sure how popular is the usage amongst the community, we could make a poll.

Moreover, I met the opinion that some powerful features of IRIS like indirection are completely useless and dangerous (I disagree of course as a fan of indirection).

I'm 100% for the usage of powerful things if we can keep readability and maintainability.

And of course, people will use the technology immediately once see the obvious value.