User blog comment:The Milkman/Extended Expectations, Part II/@comment-5124348-20120628011612/@comment-4237253-20120628015434

The thing is, they've stated this is the end of Shepard's story. Further instalments centred on Commander Shepard would be a betrayal. Their story arc is done. Since Mass Effect, Shepard's journey has been about stopping the Reapers. Going on a nonsensical adventure, or adding a new threat to the galaxy more powerful than the Reapers would cheapen and undermine our experience.

With Synthesis, Shep is well and truly dead. Their essence is completely absorbed. With Control, Shepard's body is destroyed, but he/she's mind remains, controlling the Reapers. Destroy is a much more normal ending, and there's nothing stopping Shep from seeing the crew. Instead, we're just given an anticlimax.