Insta-agro Modern RPG
Modern RPG's tend to have many hostile combatants that attack you on sight. This is to facilitate the action in their action RPG. A dungeon should be filled with enemies that instantly enter into combat with the player, just like in any combat game, like Halo or Dark Souls.
Older RPG's don't tend to have this mechanic. Lots of "hostile" characters in the original Fallout would not attack the player on sight, instead allowing the player to roam around their vacinity and even chat with them before attacking. There were behaviors that would lead to combat, but those usually involved some specific action taken by the player, and could be avoided.
Newer RPG's, however, focus on their combat as a pillar of their game. Skyrim's combat is a core part of the experience, which requires some characters to serve as pure combatants. This leads to most dungeons being filled to the brim with characters that are hostile to the point of mania.
This also leads to skills like persuasion being nearly useless outside of defined areas, like cities. There is no opportunity to talk a moderately hostile character into not killing you. Problems can't be solved with mere talk if blades clash at the drop of helmet.
This was less of an issue in early RPG's in part because combat in these games was relatively uninteresting. If your combat involves routing around in menu's, same as conversation, then the conversations can often feel as fun and rewarding as cutting throats and taking names. At least the textbox has some nuance and flavor.
TODO: Banners that you can put on your person that mark you as a combatant ready to kill, which can be tailored to the enemy.