Not pragmatic IMO - flexible usually means resonance and vibration which leads to poor finish and deafening the operator/upsetting the neighbors.

If a lighter frame was the design goal (but low cost wasn't!) then carbon fiber has an interesting stiffness/weight ratio and could have viscoelastic damping elements incorporated too. Realistically though, lightness isn't a prioritized design goal though I certainly see the appeal in marketing for home usage where you wouldn't need a crane to move the machine about.