I think it's so popular because it's so versatile. It can be dressed down with jeans or even dressed up with a blazer. Because of the knot, it's fancier than your basic tee and can absolutely be worn to work with heels. As Spring approaches we are all going to be reaching for these types of layering pieces and this one fits the bill. Sizing is true to size, but my guess is you could even size up and be just fine.
I also linked my new bag, but if it isn't in your budget, try the dupe on for size. I have one of each and I am very happy with the dupe for the price! Also check out these sunnies because they are $12 and likely won't last.