Let's look at it this way...you have 10,000 customers. About 9,000 of the customers already have the plugin. 8,000 of them bought the plugin.
Now, you, as the COMPANY, decided to give away the plugin FREE, as a gesture of "kindness", but ONLY to those who don't have it.
So, 1000 customers out of 10,000 get the "something free as a gesture of kindness" and 9,000 get NOTHING as a gesture of kindness,
basically being "penalized" for "already being a customer".
Hopefully THAT will ILLUSTRATE the "WHY" as to why this is an issue.
As I've said, they basically just told ALL of their "existing customers" to F*** off...you already got one - thanks for your money and loyalty - Happy Valentines Day!!!
The fact that most people REALLY don't think these things "through" logically is frustrating. ON BOTH SIDES.