I would not recommend this if you think you might sell the piece or move within a few years. It's nice to be able to disassemble a couch and move it through doorways much easier than if you didn't take it apart
I've never owned an ikea couch, but the big stuff I purchased like beds had metal main fasteners and were designed to be assembled and disassembled. Those don't need glue.
But I also did a chest of drawers (where you nail the backing on) and bookshelves and you just wouldn't be disassembling them. Those would benefit - greatly - from glue.
