Going along with the other replies, I disagree that this would improve the experience for newcomers. SmallString is a hyper-optimization for specialized use-cases which (I would assume) is rarely worthwhile. I would actively discourage people from using SmallString without first profiling to identify Strings as their bottleneck, especially newcomers. String will almost always be "fast enough".
Agreed that it's a very likely unneeded optimization. As shared in another sibling comment, I got frustrated with Rust's strings and figured that maybe one more complexity on top wouldn't be that bad. But thinking of it now, yeah, it's definitely a bad idea.
