In a lot of States you can’t disinherit your spouse. If one leaves a will and cuts their spouse out, the spouse can still take a heafty chunk. (50% here in Indiana). Guess Texas doesn’t have that rule.
Texas is a community property state. The property accumulated (except by gift, or inheritance) during the marriage is jointly owned, and the surviving spouse is entitle to their cut. Property held since before the marriage, on the other hand, is separate, and the surviving spouse need not get a share.