I will never accept Litecoins because I'll always have to worry that the sort of people who will jump to a similar chain will just do it again (Lightercoin?) and there won't be goods backing it when I go to get payback for my work.
Now here you touch on a
very important point, which I discussed in the OP.
It's the basis for the thread, in fact.
Up to this point most of the community imagined Bitcoin would slowly gain acceptance creeping into the mainstream, at which point its value would explode. What's interesting is nothing like Bitcoin has ever existed in the history of the world, so nobody knows exactly how things will play out.
As people learned more about how Bitcoin worked the topic of other versions of coins starting came up. Since the code is all open source and nobody controls anything, then why couldn't other coins start up trying to win support and enriching early adopters?
It wasn't long before such alt-coins did begin. The first was actually Namecoin if I remember correctly, and its purpose was not wealth creation or storage, but rather decentralizing distribution of naming rights to address government control/censorship of Internet TLDs.
Many people asked your exact question. What would prevent people jumping to other coin versions? The answer is nothing, really, except alternates would have to win support against coins having the advantage of already being established. And since there is no limit to the number of alternates that could be created they would all challenge each other as well. The result would be that adoption of any new coin wouldn't happen simply because it was new and offered the chance at early adoption. A coin would only gain favor for some specific reason, something existing which established coins didn't offer.
Soon other wealth purposed coins did pop up, like IOCoin and IXCoin, but these offered no real reason for adoption other than the early adopter play, which as explained isn't enough. So such versions went nowhere. But then other coins started that actually did seek to offer some specific benefit of use besides early adoption. Of these Litecoin has gained the most traction, as it has some neat aspects like CPU focused mining, and faster confirmation times. It was designed to be the silver to Bitcoin's gold. Vircurex.com I think gives good indication of coin traction because you can compare exchange and hash rates to see market preference.
But none of the "specialized" coins has really done much to date either. The community has only had eyes for Bitcoin. In fact, I myself only looked into what Litecoin actually did a couple days ago when I made the connection for usage as regards TBF. Any coin needs a catalyst for adoption, and I think this is it for Litecoin. Now there is a compelling reason for Bitcoin community members to adopt it: it can check the power any Bitcoin Foundation might garner over Bitcoin.
Most people probably assumed alt-coins would enter the market a some time far into the future, once Bitcoin was established and more thought went into specialized coins. So nobody paid much attention to them. However, I think the time is now for at least one of them - Litecoin.
As for the dangers of people switching from coin to coin you mention, that's what I address in my OP in the "An Unexpected Development" section. Please re-read that to understand what I mean
I plan to soon offer a Cryptocurrency Index with live exchange rates, a first step which should help the community understand what I envision.