There is nothing wrong with head voice, but, especially for men, it's really important to balance that with your chest voice. So yes, if you are losing out on the darker, richer tones, one cause might be an imbalance toward head voice and not quite enough chest.
Should you sing in your head voice?
Having a head voice for singing is necessary to access those really high notes in the song. For women, the notes in the middle part of your voice may not feel much different from the higher notes. Male and female singers feel the vibrations from singing in head voice in their head or skull.
What does singing in your head voice mean?
The head voice is described as the vibrations felt as sound that you experience in your skull or your head when you are singing at a high voice level. It is a non-strenuous way to enjoy the gift of your voice without straining. ... The head voice, if done right, comes out as soft and unstrained.