I was thinking that Book of Shadows lacks of better security. Think about it The Book of Shadows protects it self from Evil Beings. But what if Good Beings who wantes to use the book for personal or daker intentions there is no protection from that. Like when Piper and Phoebe created a man and when Gideon used a spell to force down Wyatt's shield.
And when Glen was reading The Book of Shadows in "Trial By Magic" It looks like The Book also does not protect it self from mortals, mostly because mortals are consider neutral so any basically any mortal can just take the book just like any mortal can open the door on the magical ice cream truck.