Yes shep NEEDS character development! He also needs self development like can players establish some type of pattern with him based around his psychological views on say what happened to him with the Lazarus Project or the confinement in the medical facility at Kensen's base. For instance can we use these unknown projects to help shep shepard's way of reacting to the world like if he's paranoid about his body containing reaper tech he might become unstable at somepoint (have a breakdown) in ME3 or if the player chooses shep is unfazed by potential reaper tech but embraced the idea of its use in him then shep will start to lean towards the reaper cause later in game.
Also if shep gets hacked, kidnaped, or such traumatizing things please let us have some issues on this I know I'd like to have my shep be freaked out, confused, and troubled by such things having a chance to vent with their LI on the subject would help or I could choose to confide in my best friends from ME by asking them if I could speak privately in my room with them after such a traumatizing thing. The option however would go away if shep goes onto another mission so those players wishing none of such venting would be able to be super shep brick.
Also shep needs someone to relate to maybe shep can form a student teacher relationship with a spector whose been doing that job forever and this spector could be a temp squad mate but won't necessarily disappear everytime the mission is over. I don't know lets say a temp squadmember helps you on the mission but will come onto your ship for a ride to where ever they're needed next you have to drop them off there so they can get on with their mission so while they're on ship they'll talk like normal crewmen with shep. They won't talk like Zeed and Kasumi where its a one sided conversation I really didn't like that if they're going to talk to me I want to respond to them not just stand there and stare at the walls until they're done.
Relationship development too for both LI and friends of shep sense they'll all be tested this time around.