I don't think I said wood was stronger, what I said is it's stiffer. Compare 3/4" or 1/2" plywood to 16 gauge sheet. With plywood you can throw it on top of some supports and have a decent floor with no additional work, with metal you'd need quite a bit of bracing or stiffening for it to work.
Others brought up a good point, most people already have woodworking tools around the house, or it's easier to obtain the skills needed for woodworking than for metal. I have rarely seen a DIY metal project that hasn't looked like it was DIY, while there are a lot more people can make a nicer looking wood project.
For the toolbox shown above, I agree steel is a better choice, but to try and recreate that at home would be impossible for a normal person. At the very least, I see the need for a decent size box break, shear, spot welder, normal welder, and a lot of custom fixtures to keep things aligned. Not something that you would find in the average garage, and not a small investment if you only wanted to make 1 piece. In high volumes where you can justify the cost of equipment and tooling, metal is a much better choice. For a one off project that requires a lot of custom fitting, wood is just easier to work with, you can make almost anything with just a saw and a drill.
I'm fortunate enough tools to work with both, I'll use metal if it's called for, but for some projects wood is just easier. I've got access to industrial sized sheet metal equipment, but I've done enough metal work to know that making a drawer system is a HUGE undertaking that I probably wouldn't even try it unless i was planning on doing multiple pieces.