1. More species: Voss Togruta Natoluans Nikto Weequay Cereans and more
2. More alive planets: mobs fighting other mobs, npcs walking buy from vendors, soldiers saluting you as you pass.
3. Much cheaper GTN items, and more Coins for subs. It would take me 3 months on sub coins to buy 1 piece of full set of oranges from the GTN.
Honorable mention. More lore: I want to know what happened to the Lost Jedi after KoTORII, I wanna run into Zalbaar and Vogga the Hutt, i wanna go to Citadel Station, or that village in Kashkky, the Datanoonie enclave.