Comment by krackers

> bed frames and box springs are mostly superfluous and a mattress on the ground is more comfortable and cheaper.

This is basically a Japanese futon. The only con I can think of is the one the other commenter noted, about mold buildup in more humid climates, and that mattresses are usually built assuming a bit of "flex" from the frame+box spring so a mattress on a bare floor might be slightly firmer than you'd expect.