99% of the time I care more about the quality of the photograph than babying the lens. Filters, no matter how many coatings they have, always increase flare and glare. The only question is whether the image quality decrease matters to you or not. Wide angle lenses with the sun in the shot will be ruined more than a low contrast telephoto shot. I have protective filters for all my lenses because I need them when
I'm in conditions with spraying water, etc. and I'm willing to
sacrifice the image quality.