For the same reason Valve always wins at the end, they did the bare minimun effort of doing something good, which is a rarity on AAA gaming.
Also, a quarter of Ivy's fanart was made by a single simp.

Because, say what you will about Valve, but they're able to make great characters and good, appealing. Father Grigori, a character who only appears in one level of Half-Life 2 and is never seen or referenced after his section ends is still a beloved character. Even minor characters like "Better Safe than Sorry" guy from L4D, Lazlo the guy who gets eaten by Ant Lions in HL2 are popular among fans, hell even the Rat Man from Portal, a character who never physically appears, is very popular among fans.

Concord turned people off from the get-go with bad character designs, and even if they had been well written, the fact that they're downright unappealing to look at turns people off from them.