Well, since Ringmail actually existed, and Studded Leather didn't, I'd say it has a better qualification to be there than Studded.
Studded Leather is just a misinterpretation of medieval art showing Brigandine. If we want to call Brigandine "Studded Leather" instead, I have no problem with that...just as long as it's characterized in the rules properly (play, weight and description). I'd also prefer that Chain Mail not be used, and instead just call it "Mail" (as in Mail Shirt and Full Mail), but since it's just a matter of terms with no effect on play, I can live with it.
But for play purposes, Ring Mail should swap places with Studded Leather. In reality, Studded Leather (Brigandine) is significantly heavier than Ring Mail (which is just steel or iron rings affixed to soft or hardened leather armor, where Brigandine is
plates of iron or steel sandwiched inside two layers of leather {or canvas} and "fixed" with metal studs).
Also, I think the Chain Shirt should be medium armor. That weight is way off, and it's more "bulky" than Studded Leather (Brigandine) due to it's poor weight distribution.
I was hoping one thing that 5E would do is stop reinforcing D&D as a Genre unto itself, and reflect real armor and weapons (instead of perpetuating the mistakes that were made in the very beginning of D&D and copied forward with every iteration). Apparently were starting right off with the same mistakes D&D has always had (as concerns this - for the most part, the play of these base rules works really well for me - but I do have some pointed feedback for WotC, and will likely have more...)
*(speaking of weapons, I wish we'd get away from using the terms Longsword and Bastard Sword to differentiate different weapons...they are the same thing - instead use one-handed sword for the standard Knights/Viking/Arming Sword, Longsword/Bastard Sword for a sword that can be used one or two handed, and two-handed sword for the two-handed only great swords)