1) In PoE1, most battles play out the same way over and over again, it gets boring. We should have less battles, but more interestingly-designed encounters with more variety.
Hope to see more enemies with more pronounced strengths and weaknesses, e.g. extremely high hp and regen, low hp but extremely hard to hit, oozes that multiply, glass cannons, a huge army of weak enemies etc, that will require different strategies and gear, even on easier difficulty settings.
Another aspect is to create interesting battle scenarios, e.g. split your party into groups to defend different entrances, escort a caravan, protect a fragile character. Perhaps a few epic battle scenarios which allow a 10 member party.
2) PoE's artwork is the best out there. However the maps and dungeons all follow very similar and predictable designs, the same thing in different skins. Please do not limit maps to the same dimensions. Create more variety, each dungeon should have a unique distinct archiecture, e.g. a huge open cavern, a claustrophobic labyrinth. For good map/dungeon design, please check out Wizardry 7/8 and Dark Heart of Uukrul. Good dungeon design is a lost art.
3) Create some challenging dungeons where we cannot rest or escape, forcing us to prepare carefully, test our limits and come up with strategies to survive.
4) PoE1 had too much text and uninteresting details. Just 1 interesting line will do, rather than 10 monotonous ones.
5) Rename enchanted items, customize look of item, more enchantment options such as stun and crit.
6) A workshop where we can craft various golems, which we can deploy in battle, or to carry out tasks.
7) Allow more traps to be set. Deploy temporary defensive structures such as ballistas, cannons or magic totems. Tower defense-like battle scenarios where we need to build up defenses and withstand waves of enemies.