Okay, for three sessions we played with strength damage on missile attacks, namely with the composite longbow. Last session everyone forgot that we did it with strength damage and now we aren't. Some research on other non related issues brought me to two sections that speak about damage, first page 17 under Strength:
Apply the ability bonus or penalty for Strength to all attack throws and damage rolls in melee (hand-to-hand) combat.
Then page 104 under damage which states:
The weapon’s damage will be modified by Strength, magical bonuses, and the character’s class bonus (if any).
This is interesting since it doesn't say anything about melee only.
Now, from a logic perspective, I'm not advocating for a crossbow bolt to be given consideration for strength damage, but throwing a spear, seems reasonable. Composite bow which usually take a greater pull to aim, sure, I can see it.
IANAA but I believe the rules as written are that you do not add strength mod to any ranged attacks, but you DO add fighter bonus damage.
Each campaign is a law unto itself, though. If you guys are enjoying adding strength to everything but crossbows, you can rest easy and do it. Crossbows are actually slightly above the power curve in the core game, so allowing strength to be added would not be the most unbalanced thing you could ever do (as long as the benefit was also given to monsters using ranged weapons that have unusually high strength).
I'd allow small thrown weapons to use Dex for attack throws and damage, and larger ones to use Str for both.
Makes sense to allow composite bows to use Str where it's been made with a draw for someone that strong. Someone weaker can't use it, but someone stronger can only get the benefit of the pull it's made for.