Keep in mind that Wirth is a "simplificator": given any task, he'll try to take the simplest approach (as an example see his talk for his 80th birthday and his remark on the complexity he saw at Xerox PARC which drove him to design Oberon). His languages are even designed so that they are easy to implement. Intermediate representations might be what many compilers use nowadays, but they are not necessary to write a compiler, thus they're out - sacrificed at the altar of simplicity :-).