But test mastercoins were released together with real mastercoins simultaneously. As far as I understand, you can do the same thing with test coins as with real coins. So, if there will be an exchange trading them in the future, they WILL be useful, and you can trade them back to bitcoins or whatever and buy something with it.
Still not different from testnet bitcoins.
There are so many other cryptocurrencies with hardly any innovation in them, but still they have some value, because you can exchange them with other currencies.
These alts have people advocating their use, which results in people speculating they have a chance to catch on (and they still capture only a small percentage of Bitcoin's market cap). For test coins you have no such thing.
Actually, what you're doing right here is a form of advocacy that testcoins should be used. Keep doing that and you might fulfill your prophecy.
I just wanted to mention this possibility, because ultimately, test coins might lower the value of real coins because of more supply. So it might be good to destroy them at some point, before it's too late. And of course let people know early enough about that action. I think this helps, because people can actually treat them as test coins and therefore also 'waste' them for testing purpuses.
Test mastercoins are effectively a clone of mastercoins. If you fear that mastercoins can lose their value due to the existence of a clone, and clones are trivial to create, why do you think mastercoins can have any value at all?
We already have existing test cases for all of this. For instance, bitcoin has testnet coins, which do have some value (while they are frequently given away, they CAN be bought and sold). And bitcoin has plenty of clones.
I don't see any reason things won't play out any differently for MasterCoin, although I actually expect we are more vulnerable to clones than bitcoin, since MasterCoin is just so darn easy to understand and implement and improve upon. You don't need to understand cryptography to improve on MasterCoin (I still have a lot to learn myself in fact). All you need is to be able to think of nifty things to do with messages. That's it. The distributed exchange described in our spec is ridiculously, stupidly simple. The distributed betting on data feeds are equally simple. It took me about 20 minutes and less than a page to describe how to create smart property for IPOs and titles/deeds in our most recent spec. That's one reason I'll be watching clones closely, looking for good ideas to steal
I've said this many times before: I just can't understand why someone hasn't done this already. It just seems too easy. (Although maybe it just seems that way to me since I have been thinking about it constantly for a couple of years now)