Well, it finally happened. I have been super careful not to accidentally click the "re-roll loot" button in any chests...until today. I wasted 9 astral shards accidentally clicking it. I can think of no reasonable reason for that button to be so close to the "loot" button, and to be above it no less! So I must assume it was put there maliciously, so that people would waste astral shards by accidentally clicking it. If it must be somewhere (and I personally would prefer it was not) then give players the option of permanently disabling it.
I have to click the "accept" button in a trade window a dozen times if plat is being traded, but when astral shards (earned largely by spending real money) are concerned then it just happens in the blink of an eye with no confirmation dialogue. This is severely irritating.