As Dave said the quality is superb. I think its essential the plate is strong enough to take the impact and i doubt thin aluminium would stand up the stress. The last thing you'd want is a broken or deformed plate flapping about underside.
Its function , in addition to a skid plate, is to protect the brake pipe thats otherwise at risk of impact.
After clouting the crossmember several times in the past i was delighted to find the skid plate solution - a brilliant piece of design and worth every penny.
