I always thought the KEYBOARD/Synthesizer was the weakest musical instrument in a band until I realized recently that a lot of songs I like, the Keyboard/Synthesizer is actually one of my favorite parts. A lot of time I was getting the guitar confused with the Keyboard/Synthesizer. For example, I love the "du du du du du!" Part of She Bop by Cyndi Lauper and I thought that was the guitar, but recently found out it's the keyboard/Synthesizer..
The drum is the foundation of the song, amd the guitar helps being melody and harmony.