The Gaia Garou tribes are losing the war against the Wyrm due to the mistakes of their ancestors and their inability to cooperate with each other and the Fera on a large scale. However, that's not the only reason they're losing. Gaia designed Garou to be war machines for a primitive era, intended for short-range combat and a handful of mystical gifts. However, many of the Wyrm's modern threats — oppression, ignorance, environmental harm — are rooted in social problems and destructive practices, require more creative and sophisticated solutions than small-scale violence. While a few tribes seem to understand this (namely the Children of Gaia and the Glass Walkers), many Garou do not. The Garou are losing because their modus operandi is outdated and inappropriate for the Wyrm's current threats!
In the event that the Wyrm does escape from the Weaver's web (destroying Gaia and much of the fabric of reality in the process), who is to say that the next universe they create will be any better than the setting of the World of Darkness? The Weaver will still be insane, the Wyrm might have some residual insanity from his prior captivity in the Weaver's web, and who knows what role the Wyld will play. If the Triat members do not return to sanity and harmony, the next universe they create could be just as unbalancedand doomed as the current one.
The Wyrm's madness is explicitly a result of the unending pain that comes from being trapped in the Weaver's web, and the Weaver's madness comes from the struggles of the Wyrm to escape that web. Without these, the Wyrm and the Weaver have no reason to remain mad. The Wyrm getting loose would, in time, result in the two returning to sanity and the universe to balance. Mind you, it's still a lousy place to be during the interim.