Why are so many coins released? Quite simply, most coins are forks of Bitcoin/Litecoin/etc with minor tweaks. Occasionally, you get a truly new coin based on something new, but most simply tweak the coins per block, the difficulty re-targeting rate, the starting difficulty, the block time, etc. Coingen.io exemplifies how simple this is. Of course, there are exceptions, such as the upcoming Etherium [2], the first Turing complete cryptocurrency (as far as I know, at least).
Despite that, most coins basically fail. Sure, they receive hashing power, and some even get onto exchanges. Most of them, however, don't really go anywhere.
So, yes, it is relatively easy to create and launch a coin. It is a bit harder to launch a coin that makes it to an exchange. It is harder still to make one that also sticks around and stays in the public consciousness (such as dogecoin).
Finally, let's say you have a great idea for a new coin. The way some people previously got rich by creating a new coin was to premine the coin. Basically, one would mine the first x number of blocks, before releasing it. This still happens, but is now much more often frowned upon. So, to get rich off of creating a coin, you basically would need to premine a coin, and convince others that you had a good reason to premine it [3]. This absolutely still happens, but is becoming tougher to pull off.
So yes, you could create aarondfcoin. Yes, you could probably release it and get hashing power thrown at it. But, would you make money doing so? Well, that requires a bit more effort. Keep in mind that there are hundreds of attempted alt currencies for every dogecoin success.
That said, yes, there is still room for success here, but it usually requires more than just creating aarondfcoin. The virality aspect is the more important aspect, at the moment.
[1] See the bitcointalk announcement forum https://bitcointalk.org/index.php?board=159.0
[2] http://ethereum.org/ and the whitepaper: http://ethereum.org/ethereum.html
[3] Yes, there are a still a number of ways to make money off of releasing a coin that doesn't involve premining (or appears not to involve premining), but that is a topic worthy of its own thread.