Oh, DS9 ruined Worf's entire family. They did even worse to Kurn.
Alexander appeared in DS9 four years after he appeared in TNG, and in that time he'd aged about ten years and dropped about 50 IQ points. He wasn't that great a character in TNG but he was an oversensitive kid with violent tendencies, not just a one dimensional incompetent.
Agreed on both points.
Anytime they dealt (or failed to deal) with worf's family it also made worf into a less likable character. Erasing his brother's memory without consent? Lame and dishonorable. Pretty much ignoring your only son save for a couple of episodes, where you talk about what a failure he is? Lame and dishonorable.