No particular reason, except that I'm enjoying the options. I was using Amethyst, which I don't have a problem with and, with the addition of my npub/nsec, I can try Primal.
My only beef so far with Primal is that, in the web version of Primal, I can zap sats, but not in the Android version, even though I have my Alby node correctly configured and connected. It always wants me to use the Primal wallet.
Maybe after a few months, I'll move on to "the next big client" and give it a go.