Even if they did, you can undo a blacklist. You can't undo a roll.
Now, it makes sense that they don't want you to be able to cancel a roll and re-roll again, but they can just let you change a roll to a pass. It's not much of a change to leave the Pass button active and have it override the Need/Greed result. Heck, they could let you stage down to change a Need roll to a re-roll on Greed and a Greed roll to a pass, or just go straight to pass.
I almost always pause and roll/pass on everything in the first 10 seconds, so if someone wanted a specific drop, or if they had asked and I forgot, I can't change my roll to let them have it. Sure it's my error, but I'm not the one it's a problem for.