That's a terrible oversimplification. Stimulant treatments for ADHD are not supposed to produce pronounced mood-enhancing effects. Stimulant treatment has been shown to be effective indefinitely in majority of people without increasing the dosage over time.

These days formulations like lisdexamfetamine and extended release methylphenidate are preferred because they have all-day efficacy with typical duration of action of around 8-12h which carries lower abuse potential.