Footies generally have non-rotating masts with essentially conventional goosenecks.
This means that the maximum angle of the boom to the centreline is around 90 degree, so that with the wind dead aft the sails are stalled plates.
Everything else being equal, a stalled plate will shed air in a direction at right angles to the nearest edge. This generates a resultant force in the opposite direction. Because the longest side of the sail is the leech and because the mast will to some extent act as a fence, the predominant force will be to windward and downwards.
The lower the rig aspect ratio (i.e. the shorter and fatter the sail), the bigger the downward component (in other words, the leech is closer to horizontal than it would be with a taller, narrower rig).
Since in the dead run condition the centre of effort is usually well forward of the centre of flotation, the effect of this downforce is to depress the bow.
I am far from sure how big this effect is - I cannot find any figures for the drag coefficient of a stalled plate the size of a Footy sail that look credible - but it may be significant.
Even if it is not significant per se, there are substantial advantages in letting the boom go forward of the centreline - look at any competitive Laser, Finn , OK or similar. The main remains a properly functioning aerofoil, produciong much more drive, exhibiting lower rolling tendencies, etc.
To do this? Rotating mast? Firefly dinghies used to arrange it very simply with a wire strop at the hounds on which there ran a sheave carrying the forestay. Or a gosseneck in the nature of a captive mast hoop - which might improve the geometry of the main luff as well? Another possible solution to the stalled downforce problem is to use a full-length top batten to produce a quadrilateral mainsail. This should bring the leech more vertical and hence reduce the downward component. See the Bantam and Bug designs.