Gnome didn't make just _one_ mistake. But in this context, it couldn't figure out if it was steered by committee or by fiat, so it seesawed back and forth a few times, which didn't go over well.
The standard way to move from "committee" to "fiat" is by forking, an example would be Galeon (and later Firefox) forking off of Mozilla. Or you can start over and be simple but reuse some parts, ala XFCE (done by Olivier Fourdan).
But Gnome started life as a reaction to KDE (a protest over licensing issues), which meant early on KDE got all of the pragmatists and Gnome got all the idealists. There's way more wrong with Gnome than just this one organizational issue. :)