The number of unique daily addresses used does measure a degree of economic activity, making it a fundamental measurement rather than a technical trading measurement. The amount of new money coming in is unfortunately proprietary information kept by exchanges. The importance of the two fundamental indicators of adjusted transaction quantity and daily unique addresses, as calculated by Blockchain.info [ ... ]
However, since both new addresses and transactions are free, users and programmers have no reason to use them sparingly. A substantial and variable fraction of those counts could be "fake" transactions, between addresses owned by the same person -- such as tumbling, hotwallet/coldwallet motion, software testing, etc.. Bitcoin deposits and withdrawals at the exchanges should also be counted as "fake" in this sense. The blockchain traffic may also include testing of new altcoins or services built on top of bitcoin.
Unfortunately there is practically no reliable and meaningful data on the bitcoin economy.
Transactions aren't free, they cost 0.0001 or more. Plus the time you balance won't be avaliable. Exchanges may also have withdraw or deposit fees on top of transactions fees. I don't think people would send money to themselves just for the lulz.
And I don't know altcoins that use Bitcoins transfer to test themselves. Might be my ignorance, because I'm not an altcoin developer.