I'd really like to see more customization to the uniforms.
Be able to use number/name font from actual MLB teams.
Add 2 more uniforms, Home Alt and Away Alt.
Be able to use patterns from certain MLB jerseys but have custom logos and such. For example, love the Padres desert digital tops, let me use that WITH OUT the Padres across the front.
Love customizing my uniforms just as much as playing the game. Some real creative folks out there with the jersey's alone, just wish there was more options to customize them.