A note about languages. It is important to understand that none of the ones mentioned in the OP are comparable. They all make very different trade-offs and hence serve different use cases.
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Rust is a low-level systems language. It is great if you need to optimise performance or have precise control over resources, which is why e.g. core IC canisters are written in it. OTOH, it requires much more hand-holding and boilerplate and generally is less productive than a more high-level language.
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TypeScript is on the opposite end of the spectrum, it is JavaScript with some sugar coating: highly dynamic, highly complex runtime semantics. As such, expect 100x the gas cost or more for running an application compared to Rust. (And I won’t even go into how error-prone it is, which IMO makes it a questionable choice for DeFi in particular.) Its main advantage is familiarity and the richness of the existing eco system. Python is in a roughly similar boat.
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Motoko tries to strike a balance. It’s as high-level as TS, but without the same runtime overhead and most of the other technical disadvantages. As a result, it is not quite as efficient as Rust (I’d expect something like 2-3x, but that may vary widely depending on use case). It also has seamless native support for core IC features, such as actors and Candid. The big downside of course is that it is a much less baked and familiar language, with a tiny eco system.
But it is a feature of the IC that it let’s you choose! And that it enables porting any other language, too. The ideal world is one where you can pick between dozens of tools, whatever is right for the job at hand, not one where you need to use the same hammer for every screw. ;)
Finally, to set the history straight, as @chenyan already hinted at, neither JS nor WIT nor WASI nor any other language besides Rust and C++ existed on Wasm when the IC started. Some of them are still largely WIP today, changing rapidly, and adopting them before they have sufficiently stabilised could be risky.
FWIW, Candid even had a non-zero influence on WIT. I’ve been involved with the former and have regular design discussions with the inventors of the latter.