Your wallet cannot be tampered with just by showing your public bitcoin address. However, I think a big reason
why people don't like showing their wallet is because from there somebody can see how much bitcoin you own.
This could be why people aren't comfortable sharing their addresses, because they don't want their net earnings
available for everyone to see.
Certainly, I used to hide my bitcoin address to keep off from hackers.
Once a hacker had sought how many btc wagered or how many btc you have balance, you could be their next target.
Just like in my blockchain, I don't know how does a person known my identification code since I am the only one who have known that.
However since my gmail wasn't hacked, he wasn't able to open my wallet. This is alarming because hackers are desperate to steal money from others.
Hence, protect your wallet. Don't use your main wallet your every transaction so that no one could tend an attention to check your btc balance/wagered.
What will a hacker do with your Bitcoin address? I have tons of Bitcoin addresses and none of them are linked to my Bitcoin hoard. The majority < more than 80% of my coins > are stored in cold storage. < Paper wallets etc. >
You should never have all your bitcoins in 1 address. I did the same with my bank accounts with my fiat savings. I have a account at 1 bank, where all my money is deposited and then I have bank accounts at several other banks for saving and other purposes.
If 1 account is hacked at the bank, I will not be without money. If they put limits on withdrawals, like they did in Greece then I will have money in different banks and I can withdraw what I need. ^smile^
Bitcoin address = bank account
Private key = password
You can give your bank account to anyone, and they can do nothing without the password. ^smile^