So what me and a few rpg people bugged me was the lack of meaningful big choices. If i want to i can change basically my whole equipment and subclass. No character building here. If you implement a skill tree that has choices that can't be revoked then that'd add up to the attachment to the character. If you make weapons that kinda "evolve" over time with a smart system that recognizes how you use it and suggest skills to improve it that won't get suggested a second time when you decline would make people feel very attached to weapons. Thats a way to water down the amount of guns you have to make and you can focus on effects and choices.