They are signaling they are adverse to risk. And that's fine. Some firms manage risk in different ways. IB prefers to pass the risk on to the client.
Why is this "pass the risk on to the client"?
IB could charge minimum margin and get some more commission from risky trader. I for one am happy that they don't push risk to the limit.
The clients aren't risking anything, they just need to put in more capital to trade the contract they want.