The short answer is that English just doesn't really like using its own derivational morphology.
In, say, German, when a new term is needed, it's often created within German using a combination of German morphemes, and this has been true for centuries. In English, on the other hand, it's more common to borrow a term from French or Latin or Greek.
The result is that a lot of English words consist of multiple morphemes in French or Latin or Greek, but not in English itself. If we look at the word "inevitable", for example, it seems to have a prefix in- and a suffix -able, which both appear all over the place in English. But what is -evit-? That isn't really anything in English.
The key is that this word was not derived in English but in French, where évit- is a verb meaning "avoid". So to really break down the morphology of this word, you first need to say it comes from French, and then break it down via the rules of French instead of the rules of English. (Or you can go farther back and break it down via the rules of Latin; the dividing line between French and Latin in these things is not always clear.)
So while English has borrowed a lot of derivational morphology from other languages (like in- and -able, also -ize, -tion, etc), often these aren't used to derive words in English: they were used to derive words in other languages, that were then borrowed into English. If you strip away all these recognizable morphemes you'll be left with distinctly non-English roots, like -evit-, which were meaningful in another language but only brought into English in some derived form or other.
(On the other hand, you can also find terms that are derived within English. If you look up a word like "subcategorization", you'll presumably find it broken down as sub + category + ize + ation. That's something that happened within English, not any other language.)