Yes I get your point but aren't cold storage and paper/hardware wallets good for long term investing or hodling and not for trading?
Isn't that too much of a hassle for a daily trader?
If you're scalp trading many times a day, you need to keep funds on the exchange. That's one of the reasons why scalping is risky on top of being a waste of time.
Otherwise, you can withdraw coins for as long as you plan to hold them. Personally, I only swing trade a dozen times a year or less, so I rarely have money on an exchange. I withdraw my money when the trade is executed.
Whatever you do, don't treat the exchange like a wallet. Don't use it to
store money. If you're engaged in a trade, fine. But if not, you're taking needless risk.
Also shouldn't phishing/suspicious e-mails/etc. be resolved on some systematic level? I mean if your antivirus can block connection to some bad site, why can't yahoo or gmail do the same for e-mails?
No third party service can possibly prevent all phishing/suspicious e-mails. That's crazy. It's your responsibility to be vigilant.
They already know what's written inside of your mail and they can scan for malware-ous links.
Only once they've been reported, analyzed and flagged within their system. In the meantime, you might get hacked...