You have to understand it like this, cold wallets are like vaults they secure your bitcoin unlike a hot wallet. Imagine you have $100 in cash and you would probably put it in your personal wallet or let it laying on a table and that's ok since its not a huge amount of money. Now imagine you have $100k in cash , would you put in a bag ? Of course not you would need a vault to secure the cash. And that is why cold wallets are so important, if you are going to use small bitcoin amounts for daily transactions you will just need a hot wallet.
I agree with you. But securing bitcoins are not the same as securing fisical cash.
Besides, in the region I live in right now, people don't even know what bitcoins are, you are more likely to get your wallet and phone stolen just because some petty change you had
The thief will look the btc wallet and be like "wtf is this crazy drawing?" then toss it on garbage
Now that i stop to think about it.... damn I'm in a very good spot to introduce bitcoins to local market
I'm not sure why you're so insistent on using your phone as secure storage. It is a pretty well known fact in the tech community that phones aren't as secure as other computing systems, not to mention the fact that certain 3 letter US agencies probably have backdoors in them (although most popular OSs probably do also..).