All bands have a formula for their hits. That's why they are successful. Maroon 5 has cranked out hit after hit since their first album was released (Songs About Jane). They have their own unique sound. Lots of artists want to, and do collaborate with Adam as well. Whatever his *mold* is... its hugely popular, and I love all their songs.
New artists DO need to be unique because they need to create a new sound or vibe in order to make it in an already crowded business. It's different for people trying to break in the business than for artists that already have huge fan bases. In fact when some bands try to change their sound, they will often get backlash from their fans because their original sound is what drew them as fans to begin with.