I composed the story that Walmart should create their own cryptocurrency just to ... catch your eyes

Sure.
Unless you give the cryptocurrencies to their hand, you will never persuade them quickly enough to make them learn and accept cryptocurrencies. But how to give them a cryptocurrency ? They do not have an wallet for you to send. And if they do have wallets, they are not the targeted people for us to introduce cryptocurrencies.
Giftdrop paper wallet can solve this problem first. Besides, giftdrop paper wallets have many other applications. The story of Walmart above is just an example case in suppose.
Paper wallets are the physical form of cryptocurrencies. Let's think of utilization of this mediums.
Again. How is this going to help Walmart? How will Walmart improve their business by giving out a certain coin/token? So the people now has "WAM" coin/token. Now what? Just like what pooya87 said, pulling something like this is just going to give them temporary publicity and nothing else.
No, it will not help. As all of you have said and I agree. Walmart do not need a cryptocurrency WAM. And it also does not help Walmart much.
But a company somewhere can make their own cryptocurrency accepted by their customers by giftdropping. The coin has its initial value through a giftdrop campaign because it is equal to the bonus of sale before it can be listed on an exchange. Eventually, the company can accept payment with that coin.
Is it the same way that ICOs running their airdrops ?? But an airdrop only takes crypto-citizen to its community.
Giftdrops can take everyone to cryptocurrencies.
(It seems that the story about Walmart and WAM is distracting you from the main message that I am trying to describe

Sorry for my poor language.)