Or rather, what if you didn't need exotic weapon proficiency to wield them?
Would everyone just start using exotic weapons?
Would there just be certain weapons that everyone used religiously like falcata (I keep hearing it's the best melee exotic), etc?
You'd narrow down the weapons people would use pretty dramatically. Elven Curve Blade, Falcata, Spiked Chain, Repeating Crossbow all have some really good bonuses to them that make them significantly better than martial weapons which serve a similar role.
No one would ever use a Rapier, Longsword, or Glaive.
Greatswords would still be used by a lot of barbarians, though.
They would only narrow in so much as not having to choose whether or not to burn a feat to use the statistically best weapon in category. Players who choose the best numbers will continue to do so.
On the other hand it would open up options to those who don't care as much about the numbers.