At the moment with the current gameplay there is 0 death penalty and 0 reason to avoid collisions, which can make some missions boring and slow, Hell I go afk in the middle of a asteroid field to get myself a drink while I'm on flight to the next anomaly. Collisions would make getting to these objects for various missions require actual concentration rather then just mindless flying. This in effect could be used elsewhere aswell, rather then the current mindless flight. Collisions shouldn't instantly kill you, but deal damage to your ship in some way depending on the object. For example
Asteroid/Ship type/debris objects - 10-20% shield damage located on the side you hit the object.
Planetary systems with atmospheres - These should apply a damage over time effect whilst within the atmosphere, taking damage from shields and then hull until eventually the ship explodes during entry.
Solar objects - Objects like the sun should apply a radiation effect from a fair distance, not to effect missions but enough to not boldly fly too close to them. As you gradually get closer the radiation damage should be increased.
Flying into enemy ships would may pose a problem with this mechanic, as you'll find people may use it to their advantage in combat and fly directly into people while firing all weapons. This is both a good and bad thing for combat purposes, introducing more strategies.
Perhaps allied ship collision should be turned off, As often flying in large pvp areas or deep space combat systems players often bump into each other.
I have much more other suggestions I'd like to see this game move towards to provide more in-depth feeling to the game. But I'll stick with one at a time and hopefully we gradually get there.