As stated earlier, Magic Luck and Extra Ezuipment Slot modifiers are more Rare to find on items, however you can still find it on items.
Speculation here:
#1: An earlier update involving that new players can ONLY have 8 characters per Core (for unknown reasons), they also diminishing return of the RNG% to finding EES modifiers on gear. Speculation is to make people spend more forum gold on Vault to remove fg from the system.
#2. An earlier update involving "Unspawns" to apply to items ... example ... Tier III max Stat (str/dex/int etc) of +15 can get up to a maximum of 20 when wielding Magic Luck items. Speculation is a diminishing return to RNG with the +X Magic Luck Modifier.
Thus, these modifiers are more rare on items.
Hey, just my speculation.