Problem: Need for more variety in the game.
Solution 1:
Official Option for small teams. We can choose to set teams to smaller sizes, but players are not expecting it. Every team is always "LF3M" so that is the expectation. Support for teams < 5 would be great. I prefer teams in the 2-4 range as there is more intimacy, more banter, more obvious roles and your impact is more evident.
Solution 2:
Cloning SG mates to NPCs, or a similar type of option. I enjoy the randomness of having an NPC sidekick, so it would be nice to have the ability to sidekick an NPC with costumes, ATs and powersets based on player characters. If that is too hard, perhaps simplified versions of the Costume-AT.
Have a stable of NPCs ala the Costume Slots, and select one after you enter a mission solo. If you add another member to your team, the NPC disappears after 60 seconds. If your NPC dies, your rewards are diminished by 25%, if they survive, they are buffed by 5%, or something that is appropriate.