Simplistic vs. simple
Simplistic is easy. Simple is hard.
This is a slight rewording of something Alex Limi once said during an internal presentation at Mozilla. The point is not about usage, but rather creation. Building something simplistic is easy, but building something simple is hard. The observation stuck with me, and I think it's a great little maxim.
Think about it in product design. Picasa was simplistic, but Instagram is simple. eBay is simplistic, but Facebook Marketplace is simple. IRC is simplistic, but Slack is simple.
To be clear, I'm not saying Picasa, eBay, or IRC are incapable. On the contrary, they're too powerful. I prefer the designs of Instagram, Facebook Marketplace, and Slack for what they can't do. Of course, whether anyone should use Instagram, Facebook, or Slack is another question. Even cigarettes can be thoughtfully designed.