The bridges you are referring to are foot bridges. Bridges across the Elster at Lindenau would have had to be built in swampy terrain and without the enemy knowing what you were doing. And they had to be able to support cavalry, artillery, and trains. There was no time for that.
Dulauloy was the Guard artillery commander and not highly thought of by the Guard or the army as a whole, and was considered to be 'unreliable.' He was assigned the mission of preparing the Lindenau bridge over the Elster for demolition. He delegated the authority and responsibility to an engineer, Colonel Montfort. When he came under intermittent fire, he went ostensibly to look for the commander of the rear guard, but instead of going into Leipzig, he went towards Lindenau where the rear guard was not. He left a corporal in charge, who panicked and fired the bridge early when it was not in any danger and crammed with retreating Frenchmen.
I'm a civil engineer by degree and it takes more than a day or two to build a major bridge across swampy terrain during a major battle. Anyone claiming that it could or should have been done at Leipzig has no idea what they are talking about.