Is an ambush still an ambush if your entire team goes first?
With Leadership, Wits, and gear that provides Initiative/Wits you can be "surprised" but still go first. Do you think ambushes that take place in the game should disregard the weight of initiative?
Yes to the first question. No to the second.
Unless they are sneaking up and opening with a volley of shots from stealth (a great idea for future encounters larian) then the current initiative order is fine.
The ambush is more from the enemies having ideal positioning and a properly set up battlefield rather then going first. After all, your characters could be hyper alert, hear the snap of a branch, all have their weapons out and ready to move to defend (i.e. go first) while the enemies are still drawing their bowstrings on the cliffs.