If fixed properly, it would open the door to non-string types - like, you could have a type that's entirely opaque to tcl, just a void * or whatever, accessed only through functions. This might even actually end up being a step up compared to "proper" tcl...
This would push the line count over 600, but I bet it would still come in at less than a nice round 1,000, while making the thing a lot more useful.
(I have a side project that's starting to feel like it might need a scripting language. And I always liked tcl. Must... resist... rabbit holes...)
Base64 wouldn't help much dealing with existing binary files, for example. Or network protocols, or unicode, and so forth.