For me, regular DL seem to target more hamstrings, gluts and lowerback. With the SMDLs, I can target the upper and middle back more. Also the fact I can handle more weight, and no more scraped shins is a nice bonus.
There are other reasons I like them, I pinched a nerve(Sciatica) in my lower back a year ago doing Hack Squats. Since then, I have been wary of doing DLs. I know with proper form this shouldn't be a problem... but it's in the back of my mind. SMDL, along with Partial DLs allow me to continue doing them. I wonder if I can do cleans on the SM (jk). I also think it may be a good movement for a beginner that wants to add deadlifts to their workout.
I don't think machines are that bad, they are good for a change up but not for your standard routine. I'll sometimes change up my chest/back workout and use hammer strength machines. I pay for them, might as well figure a way to use them.