While working on my research, I stumbled upon this cute illustration which perfectly highlights the changes the baju kurung has undergone through time.
So back in the 70s and 90s, baju kurung only had one common design as shown below. There's no fancy collar or fabric and the length of the blouse was knee-length long. It was simple and very modest. I would say the most popular fabric used then was songket and satin and although it remains as an all time favourite till today, new fabrics are being experimented to make the traditional garment. Since it's simple and rather plain, typically this classic design is known as the basic.
Also if you're wondering why is the right-most dress so different than the others its because that's a Kebaya. It's also a well known traditional garment worn during festivities such as Eid but it does not share the same category as a baju kurung. So we'll leave that out and look at it another time.
As of today, I think I have at least 10 baju kurung each with its own unique sophistication yet I don't think I'll ever have plenty. I mean just like our normal clothes, one can also never have enough baju kurung!