If you say it is a "terrible idea" that kind of implies that anyone who has the idea to add them to their font or use a font that supports it has made a terribl

If you say it is a "terrible idea" that kind of implies that anyone who has the idea to add them to their font or use a font that supports it has made a terrible choice. At least, that's how I interpret it. It's certainly not the most neutral phrasing.