Spring Street stage block: "It's like buying a new car and then putting it in the garage and driving a rental to work."

Regular reader J asks:

By chance, did anyone notice that Friday on Spring Street the city closed the single eastbound lane for a stage? I want to say we have a nice big stage somewhere already -- it's yellow?

Yes, sir. That'd be the Bicentennial Concert Series blocking a traffic lane, and the Riverfront Amphitheater three blocks away, perched by the Ohio.

For me, the question is two-part.

Why are we closing the two-way street we (JUST) made, and during Friday evening rush hour?

Why are we paying for this stage when we have a larger stage with an area that can facilitate more people?

Also, I seem to remember we renovated the amphitheater fairly recently. It's like buying a new car and then putting it in the garage and driving a rental to work.

The first question only now arose. The second one has been unanswered for almost six years.