The missile/thrown bonus at level 50 is 12 pts of attack.
The melee weapon bonus is 25.
The unarmed bonus is higher still (might be 50 pts).
It seems the progression is not linear, however.
The ranged weapon bonus is more than what you will get from just pumping strength and you attack at 150% speed with two projectiles at once (and extra chance to crit once you get to level 50). That's approximately a sh*tload of extra damage.
I don't disagree that focusing on ranged damage is a good way to kill things quickly and efficiently. But:
1) Using Fighters is not a good idea as they have no ranged weapon skills.
2) Putting points in something other than offensive skills is something you shouldn't do if you care about killing stuff. You simply don't NEED them. If you want to have decent defenses for the front row boost their Dex, invest in unarmed and dress them in lurker stuff.
3) High level melee fighters output more damage than ranged guys but they run out of energy faster and must engage in, well, melee range.
4) It might be possible to run 4 ranged rogues but it's probably more sustainable to use 3 (bow, xbow, thrown). I think 2 is optimal.
Note that thrown weapon damage is inferior to missiles and the number of throwing axes is quite low. You might actually run out of projectiles for all weapons when fighting the mechano-golems as they can soak a lot of damage.