Nope, your analysis is pretty spot-on. I like DOGE for some reason, but there's nowhere to really spend it. Yes, on Reddit there are people who make keychains, pens, and all sorts of DOGE stuff, but I could not live on DOGE alone. Or any other altcoin for that matter. To answer your question, they are very impractical for this very reason. I suppose they're good for gambling, but so is bitcoin.
So... Privacy-oriented coins are pretty much pointless then... Since you would have to trade them to BitCoins or Paypal balance or whatever anyway. That said, coins as of now are useless and you might as well go along with Paypal or credit card if you want to shop online. About the same amount of security and anonymity anyway.
That's really too bad, I was wholeheartedly hoping for someone to tell me "YOU'RE WRONG!" and explain why. Oh well...
Altcoins are useful testbeds for proving features that can't be easily included in Bitcoin due to any number of reasons. Altcoins with useful features that cannot be easily incorporated into Bitcoin will have value.
As far as practicality, it's too early to tell. For example, Litecoin continues to be useful despite the fact that isn't accepted by many merchants. Why? It allows for the BTC chain to be broken for money laundering privacy purposes. In the future, perhaps Monero will provide a superior privacy feature, even if Bitcoin is used on either end, because it breaks the chain of transactions.
Yes, in the future, assuming the government will fail to implement even more severe controlling measures into the society, they will be useful... But right now, in 2015 still... Well.
As for testing stuff... Monero and some other currencies use CryptoNote which as far as I know is the only truly anonymous way for coins to work. There's around 10 coins that use that so far, but having in mind what's above, unfortunately they are all completely useless. Unless you offer hitman services on the darknet or something, but that's not the case for me.
LiteCoin and other well known coins like NameCoin, NXT, Peercoin, QuarkCoin, etc., they don't seem completely anonymous or secure compared to anything that uses CryptoNote. That's as far as I have read so far however, and I'm a total newbie here. I also saw some type of privacy-related hole in CryptoNote that's been recently solved by a fork too.
Anyway, so testing to me seems kinda pointless too, as BitCoin doesn't seem to be going the privacy route, it seems to be going the opposite direction from the few news articles that I've read recently (and I'm very new in the cryptocurrency crowd so I may be wrong).