Where exactly is the problem here

Even when text-book based questions are asked, the answers come in and - the quality of English writing appears to be poor. The sentences are deformed in such strange ways, one wonders if these are works of some literary genius who can distort the English in this way. What is the problem here ?

1. Is the English impoverished due to some half-backed concepts which come out garbled?
2. May be the concepts are clear enough and the grammar is half-baked. A sentence begins in the past tense and ends in present tense !
   
3. Or May be children are not reading refined English anymore. So even if they have clear concepts and correct grammar, they just don't have the range of vocabulary to express.
4. Or they do not parse what they have just written. So they never discover the gems they produce.
   

It could be combination of these and other factors. I have no idea at this stage.