Why English language is so weak that it does not have appropriate synonyms for many words such as Motivational?

The English language is extremely strong in synonym and antonyms being that it is the largest language in the world by Word count and similar meanings of Words.

Now think about the Word. The root Word is motivation. If you add the suffix of "al" that makes the Word to mean the state of being motivating. So you look up motivation in the thesaurus not motivational. I did and found you could use suggestive for motivational or even wishful or perhaps incentive for motivational.