The most obvious reason is that it's much, much easier to design a new programming language --- especially the extremely simple kind of language that Wasabi was --- than it is to build a new cryptosystem even with vetted primitives.
The second is that the impact of any crypto error you make is very likely to be game-over, while most programming languages aren't (you can observe this empirically from MRI Ruby).
A third is that designing new programming languages, especially the simple kind that Wasabi, is a straightforward well-understood engineering task. Nobody with a CS degree should be incapable of doing it competently. You cannot say that about cryptography. In fact: many of the problems people attempt to solve in cryptography (take, for instance, multi-party secure messaging) don't even have well-understood best-practices solutions; they're still active topics of research. Not to do better, the way Haskell was an attempt to at innovating a better functional language, but to reliably do at all.
I could generate more reasons. This is just the top of my head. There is simply no comparison between the two problems. I implemented a new scripting language for building TCP/IP stacks in my first professional programming job ever --- in fact, it was the first programming assignment I got in that first dev job, and I had to do it in C. I handled it comfortably. 20 years later, and I still wouldn't be comfortable implementing most cryptosystems myself.
