Why is it not safe? Xapo has one of the most safest "offline" storage of Bitcoins and I have not heard of anyone complaining that they lost money from these services.
You are not going to store your whole Bitcoins stash on there... You will only top it up weekly from your main account, to pay for the smaller things on a daily basis.
This will significantly reduce the risk of using these services. I do think this would become more popular as time goes by and people see the advantage of instant payments.
The solution is on the table, people just need to see it.
1) only because it has never happened does not mean that it might not happen in the future, bitstamp was tagged as a safe initially, then you see a big chunk was stolen
2) if you store a small amount but the price of bitcoin rise(random big pump, certainly possible), then you might lose much more than you think, still low chances of this to happen, but not zero...
besides this i find the off-chain transaction for small things quite a good idea