Would used incorrectly

Too often I hear or even read examples of the following incorrect usages of the word "would" but I'm at a loss to explain the grammatical points in play. I would appreciate a brief tutorial on the use of the word "would" as used in the following manner:
(1) "I wish I would have" [instead of "I wish I had"]
and
(2) "if he would have done it differently" [instead of "if he had done it differently"]

In each case the use of "would" in the sentence is superfluous and redundant, but what, grammaticaly, is wrong with using "would" instead of simply using the past perfect participle or (if I have it right) the future perfect participle?
I hear it and read it often but can't explain the actual grammatical deficiency.
Can someone help with this.