While men are, generally, stronger than women, that is not likely to be your primary concern when talking about societal evolution. Murphy hit the nail on the head with his sentence that stated "many tribal cultures didn't have great population growth and males are thus a little more expendable since losing a few doesn't impact future generations as much". Especially in a treehouse society, mortality rates are going to be high* and that is going to pressure the collective to place a higher value on the people that can give birth to new life.
So question becomes:
with the heightened preference to maintain female lives, why would men stay in the village near the children and elders (the most vulnerable groups, who would generally be in the least vulnerable position possible)?
I think we can come up with a number of requirements and reasons.
1. Hunting is Not Particularly Dangerous
I understand that you stated this world was populated with dinosaurs. Overall that is fine, but I would avoid the trope that the dinosaurs are all basically T-Rex's or raptors as depicted in Jurassic Park. If even a reasonable portion of them are, leaving the village to hunt is going to be exceptionally dangerous. If the females of breeding age were all out in a jungle full of raptors as their primary activity (effectively living the human side of the movie "Predator" every day), the society is going to die off fast. Stick with tiny dinosaurs that might cause injury but probably not death. Large, predatory dinosaurs jungles work better on TV than in reality anyway.
As kingledion suggested in his comment, I would have the hunting parties mainly go after animals like monkeys and fish.
2. Inter-Tribal Warfare is Not Uncommon
Resources are generally hard to come by in a jungle and everyone wants them. Men stay at home to protect the village and scout the area around it.
Note that when a village wants to go to war it does send its men out because they are both stronger and more expendable. This is a very risky move however, as anything less than a sweeping victory may not leave enough males to defend their own village. Additionally, although women are not typically involved in aggressive action they are reasonable defenders, given that they hunt for much of the day.
If you want to play on the dinosaur theme, perhaps the "bad natural enemy" dinosaurs generally stay out of the forest but will come in and attack groups of people. They might not see an advantage in chasing around 1 or 2 hunters who are just going to escape, but when they see a cluster of people they hear dinner bells. Men must fend off or destroy these large beasts until everyone else can get to safety.
3. You Live in Trees - Things Need Lifting and Building
No reason to waste the extra muscle that hangs around the village. Goods and people that cannot climb well themselves frequently need to be moved between treehouse levels and the ground, and men supply the muscle that gets it done. They also perform jobs that involve construction while climbing trees, which is surely quite physically demanding.