I don't think it was "limited developer resources" so much as a desire to preserve blazing-fast compile times. The very rough rule-of-thumb that I've heard is that optimizations must pay for themselves (a compiler which is itself compiled with the given optimization must not be slower than the previous version).
"He used the compiler's self-compilation speed as a measure of the compiler's quality. Considering that Wirth's compilers were written in the languages they compiled, and that compilers are substantial and non-trivial pieces of software in their own right, this introduced a highly practical benchmarks that directly contested a compiler's complexity against its performance."
p44 "Oberon — The Overlooked Jewel" Michael Franz, in "The School of Niklaus Wirth".
