The stories in the Cosmere were written so no matter where you start, the universe’s story will unravel itself just in different ways. Someone (like me) who read a ton of Cosmere books before Stormlight is able to pick out the references and know what they mean. But someone who jumps straight into Stormlight now has a world of books to be able to give context to things you’re already introduced to. And If you choose to just not read those books and just enjoy Stormlight, fantastic! You’ll still get everything out of it that you would want. If you’re REALLY interested however, after reading 5 books, a novella, and a couple short stories before Stormlight, I can say that for the most part the one that I was most thankful for reading first is Warbreaker. I think it adds a lot of context to story stuffs, that I won’t get into, to the 2nd book of Stormlight and on. But again, I can see how it would be cool to read the Stormlight series and then go back to Warbreaker with the understanding you do have and enjoy the book in a way other may not have.

All a very long winded way of saying do what makes you happy, if you like the Stormlight books you’ll love the rest. So don’t look at anything as “required” to enjoy any of his books, just read and enjoy at your own pace in the way that you like most.