I'm sure there are lots and lots of options in the design space here that would have been viable, but for better or worse this is the one we got. I dunno why Pascal didn't happen (but large portions of developers scoffing at the language shouldn't be discounted: this is as much a social consenus building exercise as a purely technical one), but for the "simpler C" versus Rust question it seems to me that there's some kind of local optimum around C, in the sense that the people interested in safety wanted more than is possible with small changes to C and the people who wanted to keep C weren't sufficiently motivated to actually make the changes (Regehr touches on this in the first part of the article, getting any kind of consensus on what Friendly C should actually be turned out to be very hard).