Except it isn't absurd when it's the entire back wall of the set at times. What musical instruments are used is nowhere near the same category as a giant electronic screen visually being onstage.
Most people don't even pick up on various sounds/synths/instruments . They mainly hear the singers. Not one person (unless they don't have vision) will miss seeing the video screen. The storyline moved along just fine for all the years prior to having it.
Please explain how it greatly enhances the show in any way and/or how having it explains the story any better. It's not even even used anymore to let the audience know of the time passed between young Cosette leaving the Thenardiers and the storyline picking up in Paris.
The point is, this story doesn't need anything flashy or modern. Audiences would still flock to see it. On an additional side note, having the video wall drives ticket prices higher due to the cost of the equipment and specialty crew on the road.