Having just beaten it I completely agree. The ending was very disappointing.
Boss Battles and some dialogue between you and your siblings would've been nice.
Also the lack of a recap on the choices you had made throughout the game was disappointing as well.
Basically made me feel none of my choices mattered, I could've been an evil SOB who always chose whatever choices gave me the most profit instead of helped the most people and it wouldn't matter because the ending is the same no matter what. The only differences being in like 1 click of dialogue that each faction says at the end.