A lot of people and businesses use debt to finance the things they want to do. (Buy a home, build a new facility, pay back management). When money is cheaper, people do more.

If you can issue at 6% instead of 7%, your interest expense on that debt has decreased by 16%.

I don't think anyone expects say the fed funds rate to go to 1%, but it could go to 3.5% or 4%. [0]

[0] Fed funds: https://fred.stlouisfed.org/graph/?g=1mM6j [-] Const 10yr Treasury https://fred.stlouisfed.org/graph/?g=1nYkd