Storm Raven said:As an 8th level spell. I generally have better things to do with my 8th level spell slots than casting hopped up 3rd level spells. You may want to revise your view on the idea that metamagic feats help a wizard "keep up".
No, if you want to compete with the Fighter-15 in damage output, you better use those high level spell slots. Or put it another way - fighters don't get variable-power attacks, so it's unsurprising if it takes the best spells a Wiz can cast to match (vs single foe) the damage of a Fighter of equal level. Wizards can, like you say, do n other things also, so they can only briefly match a Ftr in his own area of expertise. If anything I find high-level Wizzes tend to dominate fighters.