Torque meters have all kinds of uses, though baker hit a couple of the big ones.
Part of what makes this event interesting is the nonlinear storage and release of energy from a rubber band, and if you don't measure the torque you can't see and manage that.
Without a torque meter, you can learn to trim a plane, and get it to fly fairly long, but you really can't best match rubber to prop to plane. You also lose a LOT of learning opportunities.
With torque you can introduce work, energy, and power to the discussion. Work is energy which is force times distance for linear systems, or torque times turns for rotary systems. For a nonlinear rotary system like a twisted rubber band, its the area under the torque-turns plot!
Start plotting those for your motors. Plot them on wind up vs wind down. You'll find a big difference due to hysterysis. You have to put in way more energy into the system than you ever get out. You can also start making clear why its so important to wind past launch torque in low sites and unwind back.
You can start making clear how your rubber band is a fuel tank AND an engine. The width of the band is your engines ultimate power, but the area under the torque winds curve is its fuel capacity. Are you flying at full capacity? Can't tell without a torque meter.
And so on.
For specifics on practical use, search this years discussions, AND last years. Ask more specific questions, etc. We'll be happy to answer.