If mods are easily removable then mod slots simply become extra inventory space...
So how about having mods take up slots depending on tier level?
Tier 1-2 only take up 1 attachment slots.
Tier 3-4 takes 2 attachments slots.
Tier 5 takes 3 slots.
Legendary mods (if they add them) are permanent and can only be used with legendary weapons.
Tier 1 mods requires a perk.
Tier 2 mods require 2 perks
etc,. for 3-5.
Could even go more in depth.
Perk lvl 1:
Using no "Workbench" to remove or replace: 30% break chance for Tier 1 mods. Tier 2 = 35%. Tier 3 = 40%. Tier 4 = 45%. Tier 5 = 50%
Using a "Workbench" have a 0% break chance to attach or replace a Tier 1. Tier 2 = 10%. Tier 3 = 20%. Tier 4 = 30%. Tier 5 = 40%.
Perk lvl 2:
Using no "Workbench" to remove or replace: 30% break chance for Tier 2 mods. Tier 1 = 25%. Tier 3 = 35% Tier 4 = 40%. Tier 5 = 45%.
Using a "Workbench" have a 0% break chance to attach or replace a Tier 1 and Tier 2. Tier 3 = 10%. Tier 4 = 20%. Tier 5 = 30%.
Perk lvl 3:
Using no "Workbench" to remove or replace: 30% break chance for Tier 3 mods. Tier 1 = 20%. Tier 2 = 25%. Tier 4 = 35%. Tier 5 = 40%.
Using a "Workbench" have a 0% break chance to attach or replace a Tier 1 to Tier 3. Tier 4 = 10%. Tier 5 = 20%.
Perk lvl 4:
Using no "Workbench" to remove or replace: 30% break chance for Tier 4 mods. Tier 1 = 15%. Tier 2 = 20%. Tier 3 = 25%. Tier 5 = 35%.
Using a "Workbench" have a 0% break chance to attach or replace a Tier 1 to Tier 4. Tier 5 = 10%.
Perk lvl 5:
Using no "Workbench" to remove or replace: 30% break chance for Tier 5 mods. Tier 1 = 10%. Tier 2 = 15%. Tier 3 = 20%. Tier 4 = 25%.
Using a "Workbench" have a 0% break chance to attach or replace a Tier 1 to Tier 5.
Or go to a Trader to have them do it but spend increasing amounts of money based on mod tier.
Legendary mods: The trader refuses to do so, unless you're friendly with the faction they're from.
.. just throwing out stuff based on wanting mods to be removable to a degree.