Looks like it would make it stronger, to step box. Metal finishing the outside edges would make possible to grind the welds down too much and not realize it, and maybe crack later on. The step also provides an area for running wiring and fuel lines, so they are not so visible.
The real reason ? Every reason is real. A fillet weld is Going to be stronger than a dressed corner joint. Fit up time is probably less than half probably a quarter. It's easier to weld Distortion would be less It's easier to run lines There's actually more surface area Doesn't look like a tube frame Ask Bill see what he thinks
C. Might be stronger?.....questionable, as you end up with a smaller box section.....Easier to weld or not.....debatable. D. Less time = cheaper to do.....(did you ever dress 40 feet of weld?).....sell at regular price.....higher profit, always thought that was the main reason....Especially with no real downside.
Let's break this down, shall we? If you were indeed an English major you wouldn't have capitalized don't in the middle of a sentence without quotation marks. Second, "Doesn't to replace Don't" makes absolutely no sense in the English language. I could get into why but I suspect it will escape you. Third, you would have punctuated after the word don't. Fourth, you would have placed a comma after the word "Sorry." See that? I quoted your capitalized word. Fifth, I don't think you understand how to use bold type to emphasize your meaning. So you may have been an English major but I'm suspecting you didn't complete your courses or your major. As long as I've been here I've never felt the need to correct someone's English until now, and man there's a lot of material to choose from! Kindly stuff your English lessons where @da34guy recommended and either offer something productive (and car related) to these discussions or be quiet.
And what does this say about you? Didn't your English teacher explain to you that writing in all caps is poor form? MANS should read MAN'S. You unnecessarily double spaced between DOESN'T and NEED. You didn't punctuate after NEED. Do you need us, sir? Because you came here with a know-it-all attitude and have offered nothing. Nothing, except professing to be an English expert yet your English is simply atrocious. Beleive me, the people here haven't begun to treat you badly. I'm ready to get my red pen out and treat you as you intended to treat others.