1. quickly 5 second math change. Most people these days don't even practice change math.
Actually, it's more of an uncomfortable situation rather than a "math" one. Some of you often don't carry cents, and you'll have to deal with the change after one of you has paid the merchant. Also, it's often difficult for small businesses to have lots of liquidity of banknotes and coins. You're not going to give a $50 banknote for a <$2 transaction, because it's just considered annoying from the merchant's part.
2. extremely difficult to track. Due to centralized exchanges, Bitcoin suffers from poor untraceability for the majority of users.
Well, if both you and the merchant use a centralized exchange, then yeah. But, if not, you're making it less trivial. Also, lightning network provides sufficient privacy for micro-transactions.
It is very difficult to move millions of dollars with cash, which is the only justification I would accept for why it is bad.