Pretty sure without some kind of system like warriors/monk have Rogues are always going to feel a bit... one buttoned.
In terms of dps, we're in a pretty good place as far as I can tell - there are definite limitations on our ability to do damage, but for the most part those are shared by other melee dependent dps'ers. The problem is that those other classes have better developed and defined utility.
Some more ideas, some bad, some good:
Rogue Disguise Ability -- would be a quested clicky item which (1) shapeshifted Rogue into current target; (2) modified faction
Cavity Search -- pick pocket on an npc corpse would yield a chance of additional cash
Bleeding Wounds -- hits with a piercing weapons against the living have a chance to cause bleeding wounds, weakening the target
Glyph of Offense -- Similar to the caster resist adjust glyphs, but increases melee accuracy (not-Rogue specific)
Nightblade's Grace -- Expand the list of things this spell dodge works on (currently seems to be only things that cost a mob mana?)
Innate Trapfinding -- Anytime a Rogue is sneaking, they automatically are making sense trap checks, maybe as part of the Ambuscade Expertise tomeline
Trap Dodge -- give Rogue a chance to "dodge" trap triggering, maybe as part of the Ambuscade Expertise tomeline
Trap Pets -- Line of traps that spawn swarm pets -- e.g., clockwork rats
Distraction -- Successful "You see an opening" - "Got em!" causes the mobs next melee swing to miss
Fast Stealth -- Rogue moves at full speed while sneaking - something quested, i.e., advanced Rogue skills training
Selfless Evasion -- similar to Warrior /shield, Rogue /evade targeting another player would shift a % of Rogue spell avoidance abilities to the other player
Skeleton Key -- quested/crafted Rogue lockpick that can be used to open a wider range of locks (e.g., chests/doors that usually require a specific key) - poofs on use
Reverse Pick Pocket -- Pick pocket with an item on the cursor and npc targeted gives that item to the npc (e.g., armor with negative stats, loading up mobs in a newb zone with surprise phats, etc.)
Knives Knives Everywhere -- AoE throwing
Focused Evasion -- Take reduced damage while hidden -- i.e., a properly timed /autoattack off and /hide could save you from an aoe/db/etc.
Trap Scaling -- currently only the damage effects of traps scale, would be nice if all effects scaled
High End Stolen Goods -- Rogue fence quest for items pick pocketed from high-end mobs (items would be on separate pick pocket loot table)
Separate Pick Pocket Loot -- Instead of pick pocket coming from a mobs normal loot, it would be a separate thing - e.g., a mob with 10p of normal loot would also have 3p of extra loot a Rogue could find
Door Locking -- Rogue can lock doors that would otherwise open normally (most important for the Athica bank)
Targetable Poison -- click on poison while targeting a group member = group member gains poison proc
Contact Poison -- powdered poisons which are clicky items rather than procs
Locked Boxes -- Dropped loot that requires lockpick skill to open, can be bashed/blasted with spells but results in inferior reward