Then Staind may not be one of 'em. I've seen alot of artists change their perspective in music over the years. Alot of top Dons in music have changed styles to stay up with the times or meet a new feeling. Just for example (don't attack me on this) take Disturbed, The Sickness was alot of anger, hate, and hurt passions. Believe was more docile, some anger but more leaning towarRAB making amenRAB. 10,000 Fists is back into that anger but more heavy hearted, there's a kind of sadness to it almost.
Point being, to those who's music is a way of releasing their feelings their music changes with their emotions. To those who's music is about how they live or just modern life and styles in general, the music changes constantly with time.