It's SOP - particularly in schools which offer no athletic scholarships or aren't fully funded on the athletic side. Additionally, if a kid can get pure FA in an amount at least equal to the available athletic scholly, coach may not be forced to use his athletic money. This is in addition to any academic money (which would not require a family's financial info).
Basically, the coach has three buckets (four counting the recruit's family) from which to finance his team and moves pieces around until the puzzle fits.
With the typical 60k private school price tag, the coach needs to know if the family can afford any residual amounts. Sitting with an FA officer means the family learns the unvarnished truth (as much as a person without the same interests can be) of how much they will need to come up with to attend. If the family can't afford it, why not learn early? (With a 60k price tag [of which 45k is tuiition] and a 25% offer, a family needs to come up with roughly 38k annually because the offer is keyed off the tuition number - not the total amount.)
Also remember, the school is rolling out a team of officials to sell the deal - resist doing anything other then completely understanding all the economic consequences; resisting can be difficult when you and your son are the center of some very flattering attention.