> But it's funny how, for many features that were added later, people were rationalizing their absence with such lines too

There's nothing wrong with that. If string interpolation is really useful, then Java will add it some years down the line.

It's cheap to add features but literally impossible to remove them. There's no way to undo a mistake in language design. That's an asymmetry. I'd rather err on the side of caution than kitchen-sinking it.