Did they sacrifice their artistic integrity? No. Actually they are constantly growing as an artist with every album and learning to become better song writers and musicians. Did they do it to be more popular? No. I think many of us have already read the rant by Mike after ATS where he explained that accusation. Did they forgot their roots? I don't think they have, you can still hear Linkin Park sound in their every album, and by thinking their first record as their only root is in a way bit stupid, because the band has said many times HT isn't the only sound the band can do.
You don't know why they changed their sound, so stop saying "everybody know that". And to your second point, you are pulling those percentages from your ass. Actually i think if you go asking people what's their favourite LP song, i easily could imagine most people answering In The End, One Step Closer, Faint, Given Up or other songs like that which are all at least a bit more rock.
All videos where he said those or didn't happen. I honestly don't think Chester has ever said HT is better than MTM and Meteora. And even if you could provide the links (which i doubt) of course your taste in music can change. I sometimes say From The Inside is better than Faint, then sometimes i think it's the other way around
My english isn't the best but i hope you get my points.