Word Roots are a Part of History. "Histories Make Men Wise" -- Bacon.

Why Old English Words are Not Eligible for English Word Roots?
As an English learner, it is disappointing, puzzling, and even shocking to me that:
1) English words are basically not originated from Old English, but rather from Latin, and Greek through French.
2) Stem of an Old English word is basically not eligible for being a root of modern English word.

As I investigate, the reasons are:
1) Possible breakage of western civilization if Old English words are used as word roots. Western civilization originated in Greece, flourished in Rome which incorporated science and technology from Greece. Rome used Latin. French is basically a descendant of Latin. It is through the Norman conquest of 1066 that French was brought into England.
2) Old English was mostly spoken by lower class illiterate people, like those in farming field; Latin was spoken in churches and academies (Remember that Newton wrote his most famouse book 'Philosophiæ Naturalis Principia Mathematica' in Latin.), French and Latin were used in courts and royal palace in England.

A small list of Old English words versus their corresponding words (with same meanings) from Latin or French is given below:

Old English Word		Latin Word
pig or swine		porc
cow		beef
sheep		mutton
fight		conflict
love		amour(a Latin root)
woods		forest
thorough		complete

As answers presented on reddit: class reason
"Latinate words generally have higher prestige associated with them than Germanic words"
"Old English words are simpler and more casual, Latin words have connotation of being more fancy and more educated."
"French was seen as the language of the rich whereas Anglo Saxon was for the lower classes."

It is remarkable that only a small amount of Old English words survive into morden English. However if they survive, they usually become the most frquently used words in English, as you can see in the list here.

Many Old English words disapperaed and were replaced by Old Norse words as can be seen in the list here. These Old Norse words are like Old English words, they are not used as word roots.

Many people on internet say: (Greek and Latin Roots)
"If you studied Greek and Latin roots, you will have better speaking and writing skills."

For those interested, you may want to look at the side note at the very end of this page, where some English words are indeed created with the stems from Old English words.

Notes on the Construction of New Words
The web pages here are all about the dissection of an English word into its constitutient root, prefix, and suffix, and about the derivation of word true meaning accurately from the them (Please see Greek Roots Part and Latin Roots Part. on Learning English Roots ). Once you learn how to dissect a word, you know how to construct a word from the roots, prefix, and suffix. Because everyone is quite familiar with the words in the List of Most Frquently Used English Words here, under some special language context one may be inclined intuitively to construct or compose "new" words out of the stems or words from the List here. However four points are remarkable:
1) Because basically only Latin and Greek roots are eligible for coining or inventing new English word (please see the reason above), if you attempt to construct "new" words out of the stems or words in the List here, you will get frowned upon by all people across the Europe (including the people in England). Instead you need to think about constructing or composing "new" words out of the Greek and/or Latin roots, this is much safer.
2) It is usually safe to add prefix and/or suffix to the words in the List here to construct or compose a new word. And very often you will find that the words that you thus compose appear in a dictionary. (What a hilarious experience when you find the word that you compose in your mind does appear in a dictionary!)
Some examples:
rework = re- + work
undoable = un- + do + -able
creative = create + -ive
clarity = clear (varied as clar) + -ity
speechless = speech + -less
lovable = love (varied as lov) + -able
biweekly = bi- + week + -ly
afloat = a- + float
mindfullness = mind + -ful + -ness
3) It is also safe to add prefix and/or suffix to the Greek roots and Latin roots to construct new words. A word thus constructed carries a connotation of more education than the word constructed out of the stem or word in the List. Because a user will find tons of examples in the web pages of "Greek Roots Part" and "Latin Roots Part", examples are not repeated here. Please click Learning English Roots and then go to Greek Roots Part and Latin Roots Part.
4) As you learn more and more Greek roots and Latin roots, you will be able to construct more and more meaningful words in you mind, and quite often you will find the words that you construct do show up in a dictionary. If this happens to you, then the goal of our web pages is realized. We will be happier than you are!

Side note: examples for English words that are stemmed from Old English words are:
seafood, bathroom, aircraft, greenhouse, ballroom (where ball is actually from Latin, and eventually from Greek, which means dance), brotherhood, welcome, mastermind