Because the feedback on how they worked apparently wasn't that positive.

Also who cares having to use String.format() in the agentic coding age?

Interesting point - syntax sugar was nice when writing code by hand. Now we'd be fine if no such sugar was added anymore ever again.

Honestly, I still write a lot of perl, and while interpolation is nice and good to have for simple things, I find myself using sprintf more and more in production code, especially in the cases the examples always show off, such as needing to alter the variable, add two together, etc. I assume those are just shown to illustrate you you can do that, and not imply you should, because commonly using arbitrary code execution within interpolation is something I'd feel compelled to beat out of my coworkers if I encountered it regularly.