Because nobody knows what an SC is internationally and Aussie SCs have to explain themselves. And yeah... if you're an SC, you're probably in the running for a lot of high-paid overseas jobs in England, Canada...etc. TBH I thought they'd already brought back QCs for this reason... I guess not in NSW?
In my experience (not as a QC... sorry I'm not that good) it's often impossible to explain your qualifications to employers who have NFI.
Even a JD to be honest. I've had many lawyers say 'you need an LLB to work at a law firm you fool!!' They ignored the rest of my resume/application and assumed I was some ultra-foolish paralegal who didn't quite understand the legal fraternity. Not a problem now, but I can understand why a lot of oldschool people (who are usually the ones handing out the good jobs) simply don't know current terminology.
IMO it's a risk with the JD to be honest. JD makes it more appealing to international students who want a JD (because you get a JD in the USA.) Will the term stick? I dunno. Unfortunately I didn't have the option of doing an LLB so this is something that will always be a part of me. Doesn't matter now (I'm employed and experience speaks for itself) but re-naming a professional qualification can have some serious consequences.
Rant about my previous life
In a previous life I was a teacher. The NSW Institute of Teachers (now called BOSTES... go figure) told me I wasn't a qualified teacher because I didn't have a 'Bachelor of Teaching.' Telling them that 'there was no Bachelor of Teaching at my university... or most in my time TBH you fool... it's a Bachelor of Education and I have a Master of Education as well so if anything you owe me a whole heap of back pay because I forgot to put my Masters on your books' went absolutely nowhere because some stubborn office clerk (with NFI about teaching or teacher qualifications) had it in her head that I wasn't qualified. By the end of the conversation it was good being able to say 'well you know what... you can shove it anyway! I am a qualified lawyer not and was only paying your stupid yearly fees because I thought that one day I might feel like going back to the low-paid, under-resourced teaching profession. I'm employed as a lawyer and can't be bothered arguing whether my teaching qualifications meet your new standards...'