> Spanish is totally systematic in this sense and once you can read it, you can pronounce it.

IMHO purely phonemic orthography makes orthography unnecessary complex, as there are language features like assimilation[1] that happens naturally in spoken form but does not make sense in written form.

In contrast, morphophonemic orthography keeps systematic and consistent mapping between spoken and written form for individual morphemes, but not necessary for words, as in written form morphemes are just concatenated (to make words), while in spoken form there may be complex interactions.

[1] https://en.wikipedia.org/wiki/Assimilation_(linguistics)