I had a game today during which I benefitted from using a colony late in the game.
I was playing as Germany. I was the leading power on my home continent, but I still had a respectable rival (Babylon- I was No. 1 in the world, but Babylon was No. 3). Babylon had the only source of Rubber on my home continent, and it was next to one of its old core cities. I conquered that city, but I razed it out of culture flip concerns. I then used one of the workers generated after the razing to build a crucial Rubber colony.
I could have built a city there instead of a colony, but it would have been too close to other cities and interfered with my city spacing scheme. I ended up building a suitably spaced city nearby the turn after I built the colony. Eventually, that new city grew enough in culture to eclipse my Rubber colony. But for the 10 or so turns needed to grow the culture, the Rubber colony enabled me to churn out units.