But werewolves have a history of devastating the land and spreading their curse. Why wouldn't they do it again?
I think it could be argued these werewolves are different from the rest.
Well at the battle of Denerim, I actually thought that having 50 archers was better than having 16 werewolves, but igoring that. Elves could provide more than just guerilla. They would provide ranged support, which is always needed imo, and reconaissance. And also numbers (from the other clans, though I wish the game shwoed them because yea, we don't even know if there are clans nearby). Also, the Night Elves were with Loghain throughout the rebellion, And I am sure he fought pitched battles other than the River Dane, so them fighting in those battles is likely. I might have to check up on that later though. Could anyone confirm?
And I think that in 3 of the 5 combat situations, the werewolves are superior to the elves at Denerim.
Elves could provide ranged support and reconsecrating, but how useful are those really?
Ranged support is all nice and fine, but beyond the opening of a Pitched Battle on Open Ground, ranged support does not play a major role. The Cavalry and Infantry win the battles, not the archers.
The most famous example in Medieval History of archers supposedly winning a battle was Agincourt, but Agincourt was not won because the Archers slaughtered the French with their bows, but their daggers, mallets and swords due to the mud which had made it hard for French Knights to move.
In close proximity, Archers CANNOT use their bows, they have to fire over friendly units so they don't hit their own men, this make wildly inaccurate and almost useless. If they own a hill they can still fire quite accurately. However in Denerim you fight in a burning city with narrow streets, in such a tight place Archers would be all but useless
There are already scouts in Fereldan, and mages can apparently use their magic to see in the distance, and having scouts is useless compared to having more useful fighters in the actual battle.