In Present progressive^x, Simple past^x, Expressions^x

Hi everybody,Why do all the Grammar books use the expressions "simple present" and "simple past", although all the other tenses start with the tense-marker and add the aspect-marker then: present progressive, present perfect, present perfect progressive, past progressive, past...

Hi everybody,I'm a teacher of English at a German Grammar School and after 12 years of experience I'm still wondering about the following puzzle:Why do all the Grammar books stick to the "confusing" expressions simple past and simple present, although it seems quite more logical...