What is the use of having a DSR or a feedback system if you are forcing your buyers to give you 5s all day long? How can anyone trust a skewed system.
If it makes you feel better maybe ebay should start a new policy on pre approved bidders with a option of not allowing bidders who do not support excessive shipping standards lol (Joke).
On a serious note, The OP is not excessive in his shipping charges inb my opinion. But I dont think anyone should be held in contempt or threatened because they choose to leave a feedback they deem reasonable. What you are basically saying is "Dont bid on my items and win them unless you are willing to leave me 5 stars". Thats defeats the purpose of a feedback system. Not saying you dont deserve more than 1 star in this case. Just stating that it works both ways if you are looking for honest feedback.