The original technique seems to have been made by the Ryujinn, a race we don't really know anything about beyond the fact they're probably similar to the Wish Dragons. Presumably the Namekian Dragon Clan are just the only remaining sect with enough knowledge to create their own, still.
Basically, it's probably not unique to Namekian physiology. But they are probably the only ones who could teach someone to do it. The Nameless Namekian somehow has Dragon Clan knowledge, so Piccolo might be able to teach her.
Alternatively, Shenron would almost certainly know how to make other Dragonballs. But he'd probably charge a Wish for the knowledge, and we don't really have a way to safely use the Black Stars at the moment.
I actually like the idea of Crane as our signature school (until we start building a unique style anyway, probably mixing in Ancient Saiyan stuff and a few Namekian tricks from Piccolo), but I just think Turtle's a little safer for picking up the basics before whatever thing that's about to happen, happens. It's an inherently defensive style, so you're less likely to just get flat out cold-cocked if you encounter an opponent with greater skill.
They're both derivatives of Mutaito's style, so crossing over to Crane next turn shouldn't be particularly difficult.
