> Interacting with objects instead of text is definitely a huge plus.
It's a huge minus. The fact that all shell tools produce text is a basic tenet of shell programming which underlies the composability and interoperability of them all.
> the main benefit of bash is the portability
No, see above. Also, you probably mean ubiquity rather than portability.
> If you spend most of your time in the Windows ecosystem, then there's no reason not to learn it.
The reason is that it will make you only work with other tools by Microsoft, or at best some Microsoft-centric companies which write such tools. Those tools might gain some benefit from working with non-textual objects, but the detriment in variety and composability (even ignoring multi-platform work) is massive.
Another detriment would be how it's non-shell-like work. Part of the idea of shell scripting is that it's work that you might have done "yourself", manually, manipulating the text. With something like PowerShell - you need a debugger, data viewers etc. In fact, one could argue that PowerShell is barely a shell.