I can't quite put my finger on why, but I've gradually transitioned everything off it over the past few years. I think it's been a combination of the ease of AWS, along with Heroku's changes to their Dyno pricing, but I never actually sat down and did the math. It just started to feel a little less controllable and a little more than I wanted to pay. To be fair, their database tiers were pretty pricey, so this article is nice news.
I'd be curious to hear if others have had a similar experience?