Yeah, I can't really see heavy cotton long-sleeve t's and denim pants working for me. I really don't like the feel of cotton once it's wet (and it's bound to be one way or another when I'm riding, either sweat or rain or both), it's heavy and clingy and doesn't dry quickly. Denim is similar, but is even heavier and also stiff, not nice wrapped round your legs when you're trying to pedal. And in any case, while both would be a little better at protecting you than lycra in a bicycle crash neither really offer much in the way of abrasion protection. Just ask any motorcyclist/cyclist who's slid down the road wearing a pair of jeans and they'll confirm that...
Personally I find the technical fabrics of cycling gear much nicer to wear when riding, they're light, form fitting, sweat wicking, quick drying and breathable. Unfortunately they offer negligible protection in the even of a fall, but what I'm after is adding abrasion resistant bits in strategic places (hips and arms, the bits that tend to slide along the ground when crashing a recumbent) rather than abandoning cycling style gear all together. Elbow and forearm guards together with kevlar/leather reinforced shorts seems the way to go, effective protection against road rash but without restricting movement, getting too hot or adding much weight.