How about building inflatable space stations? https://en.wikipedia.org/wiki/Bigelow_Commercial_Space_Stati...

Or mining asteroids?

https://en.wikipedia.org/wiki/Planetary_Resources

For my money, either of those is more "visionary" than "a rocket booster that costs somewhat less than previous rocket boosters".

Now granted, they're both a lot less practical, and it's true that making things cheaper is often a crucial first step towards making them better.