Don't expect so many airbags and crumple zones as in most modern cars, just look at it as "better than soaking under the rain on a motorcycle" if you want so. Not even ABS brakes were a popular option back in the day, even though those could technically be retrofitted, but most people looking for an Opel Corsa B simply as an affordable commuter won't even care about it, especially in a country such as my homeland Brazil.
Some replacement parts at least matching the quality of the original ones might not be so easy to find anymore, but it's still not so much demanding when it comes to maintenance. And when taken proper care of, its engines are going to last long.
Another aspect worth mentioning is the Opel Corsa B was still small, in contrast to newer generations of "small" cars which are bigger than some cars that used to be seen as large 30 years ago. For someone willing to use one as an urban commuter, the compact size and ease of maneuvering on tight spaces is a good motivation to at least lurk about how good an Opel Corsa B might still be.