This means nothing just like the number of transactions which is made by Bots (faucets , gambling websites & exchanges) and people keep losing their passwords & private keys so they logically make another wallet (by ignoring the fact that online wallets are the worst wallets to use) .
Satoshi advised us to use a new address for every transaction if we wanted to remain semi-anonymous. Some blockchain.info users might be creating a new account for every transaction, which would create the illusion of masses of new users signing up each month. The amount of active wallets constantly being reused might give a better indicator of the amount of real blockchain.info users, though that would discount those users attempting to remain anonymous.