Seamers cannot get wickets (consistently, against top batsmen) without deviating the ball through the air or off the pitch - it's just that quality seamers can move the ball on any surface (if it's not seaming, bowl cutters and Off-Break\Leg-Break slower-balls) and can also bowl either conventional or reverse swing depending on what state the ball is in. Swing completely takes the nature of the pitch out of the equation.
Wristspinners will turn the ball on near enough all surfaces - not always the same amount, but pretty much always.
If, by "small amounts of turn" you mean an inch or two - no, 'fraid not. No ball turning by less than a bat's width is likely to cause problems at 50-55mph, even if very full. Bowling good lines and bowling to your field is all well and good, but all it'll do is keep the runs down. Good bowlers are generally pretty good at doing this - but they also need to take wickets. Changing pace and length, too, is all well and good and neccessary for any bowler - but at 50mph stock-ball it won't get wickets by itself. You need to move it sideways. Likewise - bowling a ball that goes the other way is no use if neither the stock-ball nor the wrong-'un turns - it's just exactly the same. Variation is only of use if your stock-ball moves (or, of course, if your variation moves and your stock-ball doesn't - but that's damn unusual).
Finally - flight is all well and good, too, but you're only going to achieve 2 things with this:
Loop - the ball pitching shorter than the batsman thought when seeing it out of the hand. Very useful - but only if the ball turns as well.
Drift - almost the spinner's equivalent of swing, as turn is of seam\cut for seamers. Almost. Drift is essential for all good spinners, but unlike seamers it's only a compliment for turn. It won't get good batsmen out on it's own - because good batsmen can adjust to the ball at 50-55 as they can't adjust at 75-80.
For a spinner to get wickets, he has to turn the ball. That is simple reality. Even the like of Derek Underwood, who could quite possibly have bowled at 65-70 mph, rarely troubled batsmen when the ball wasn't turning, and as such was infinately more effective pre-covering than post-covering.