When the C was invented? I feel it'd have been much more burdensome and inhibited the authors of various compilers if they had to write software or otherwise emulation of all these lenghths on the archs of the time. Still today I'd say, you cited size_t, I think that's the most important type, otherwise we shouldn't make most uses of integers as named fixed lengths unless we are specifically performing some mathematical operation like finite field arithmetic where the bit length matters or as you noted you know your problem size might be large enough that some archs machine words are too small. Otherwise I don't see why we shouldn't just default to natural lengths. Otherwise we need to write different int types for each arch and that doesn't sound nice unless we explicitly see a reason to.