road form, that is the way you ride a road bike, there is more back and forth transition from

seated
to
standing

that is, the way you use your muscles
the way you mix up the use of muscle groups.
i.e. seated climbing, then stand and run on the pedals, seated, repeat.
a big lead out to a sprint... so you're seated cranking out the speed, and maybe suddenly you have to stand for a sprint.

the steep seat tube angle facilitates an easier transition from standing to seated

touring bikes, by design handle racks, and panniers.
a majority of your "touring form" that is the way you ride a Touring Bike, is mostly seated.
standing to crank a loaded touring bike is not the preferred method, rather to sit and spin the gear, hence the popularity of a triple.

a slacker seat tube angle also allows the rider to push back, and apply more torque to the pedals while seated as compared to a seat tube angle that is more upright, where the saddle would be more directly over the BB.

so you'd see a road bike with a steeper seat tube angle typically using 172.5mm crank arm length
while
a touring bike with the slacker seat tube angle typically using 175mm crank arm length

to further expand the example, look at track frames, where the seat tube angle is steeper yet yet, and cranks are typically 170 or 165mm length, where the spin and quick out of the saddle sprint is crucial.


you can somewhat fudge this aspect with both bikes, by sliding the seat rearward, or forward on the rails.
but in reality, there isn't much you can do to change those angles outside of using a seatpost with some setback, or more popularly these days, you see Zero setback seatposts....

hope that helps