I can empathize with the author on wanting to leave when not feeling like an essential part of a team. Personally, I like coding and designing, and definitely I like being part of a team and working towards a goal. But for all the dev managers out there: try to inoculate some form of ownership, so that your devs feel a sense of belonging.

Its not so much that I actively seek to leave when that happens as much as I become more receptive to other opportunities. And recruiters and other companies are very good at luring candidates, so it all adds up.