Since smart phones got really big people are used to technology streamlining things and making everything work smoother. THey expect technology to just work and require minimal intervention from themselves.
Cold storing your bitcoins may be smart but a lot of people just can't be bothered with the extra steps. Also, to actually use the bitcoins you got to make them hot again so what's the point unless you're planning on spending them all in one go?
I understand the hassle but if your going to invest a large amount of money into Bitcoin people need to make these steps. A couple weeks ago there was a story on /r/bitcoin of a guy that had 30+ bitcoins stolen from a hot wallet, I don't know about you but almost $30,000 seems worth the hassle.
f their computer is infected with trojans or keyloggers they can get your money off a paper wallet before you even send it or when you try retreave it.
This is why its best to use a computer that has never been online before.
Or use a linux boot CD. Wallets are only as safe as you are. Blockchain.info is very also safe as long as you remain so and take advantage of all their security features.