jason et al make a good point--compound functional movements are ideal in most instances in terms of their ability to develop the athletic qualities we're after, BUT unfortunately there are circumstances in which they're either inappropriate, inadequate or even potentially dangerous. as a trainer/coach, unless you're fortunate enough to immediately land a position in a professional team or similar, you're going to have to deal with individuals with less than ultimate capacity, athleticism and conditioning. in these cases, no amount of brilliant coaching cues or articulate discussions of the beauty of natural movement will be sufficient. the ultimate goal, of course, is to bring these individuals up to a level at which they're capable of performing these higher-order movements, but there must be a progression and part of that progression is their relearning body control. certain isolation movements are appropriate for this.
anyone familiar with CF has been indoctrinated with the notion that all isolation movements are strictly bodybuilding movements and have no place in athletic training--but a survey of successful coaches and programs will demonstrate that this is simply not true.
there are even odd cases like that jay schroeder makes for allowing his players to perform curls--curls make big arms, big arms make confident players, confident players play better. that's about as indirectly functional as it gets, but if you get past the initial knee-jerk, it's legitimate. not that i agree all athletes should be doing curls for this reason, but the point is that blanket statements like "isolation exercises have no legitimate uses" don't hold water.