Personal preference. Perks include consistency and hackability. Mutt for instance hasn't changed a whole lot in decades. The relative simplicity and stability a

Personal preference. Perks include consistency and hackability. Mutt for instance hasn't changed a whole lot in decades. The relative simplicity and stability also means I'm not running into a whole lot of bugs. GUI email clients on the other hand... Resource usage is also about as low as you can get.