Probably the same reason they killed him off the way they did: to exploit his popularity for cheap reactions.
The funny thing is it all came across as disingenuous because none of those characters were ever shown to really care about Wally in a meaningful way. I mean, Artemis' talk with Bart at the end of season two was way more significant than any moment she had with Wally from her side of things.
Well, sure, but the situation is quite different.But Wally retiring *does* have precedent. That's the only point I was making.
And it would be one thing if those involved with the show simply acknowledged the failings of the character. Instead Weisman wants people to view him as a better hero (in terms of heroic nature) than Barry and Bart while the show constantly showed that wasn't the case.