I agree that using the MCP button is in the ‘why would you want to?’ category and deliberately using the trim to disconnect isn’t a good practice. Either technique would probably be questioned, both on line or in the sim.
Re the disconnect bar, the -800’s I fly (mix of older NG’s and almost new) all have the bar. I seem to remember an internal report that a crew couldn’t engage the autopilot until they pushed the bar, which was fractionally out of place.
Anyway, heres one from a zoomed in bit of a photo I took a few months ago.
