The Etymonline link in your question says that suffix -red " is analogous to -hood, which has replaced it in brotherhood, neighborhood, etc.; it survives in about 25 words."
Wiktionary's list of words derived from -red consists of just 15 words, of which only two are common:
With the exception of cantred, and hundred which has appeared on this list inexplicably, all of these words are formed from the Old English suffix -reden. None of them were coined recently by any stretch of the imagination; in no way is it an 'active' suffix, as Etymonline claims. Dictionary.com even says that it was only "formerly used in the formation of nouns."
Modern coinages are generally formed with -hood, -dom, or -ship, never -red. This is presumably because kindred and hatred are the only words in common usage that were formed from this root- its rarity means that few people even know that it's actually a suffix, and nobody's going to coin a word using a suffix that they're not aware of.
This passage seems to hold the clue, but part of it's unfortunately cut off on Google Books. From the part of the book that is viewable online, the author says that the suffix was lost in the Middle English period. I can't see the whole argument, but she writes in the chapter's conclusion that "since a 'stronger' suffix had already existed for a long time, native -ness, formations with -reden were ousted by formations with -ness."