Oh yes please, i want something like that too, here's my take on it:
Each weapon should remember its last used attachments (F6) and fire mode (X) when changing weapons (also after logout). If 1 or 2 attachments are not in the BP, it should only auto equip the ones that are in the BP.
Auto equipping random attachments is not a good idea, because if i don't want to use certain attachments with my current weapon, i will always have to detach them if i just picked them up for a different weapon.
Also add an On/Off setting in the options menu please, so players who don't like it, can turn it Off and nothing changes for them.
Would be really awesome if you'd consider this suggestion, because i am changing weapons in slot 1 frequently (drag'n'drop) and it is quite annoying having to attach 2-3 attachments every time, especially if i aggroed a bigger horde of Zombies or being chased by a Superzombie.