I also question whether or not an exchange that just matches it up with LTC would be a disservice since it creates a virtual wall there. Instead of "Wow, this is worth x BTC" it becomes "Eh, it's worth x LTC but I don't really want to trade into/out of LTC."
To put things into perspective...
LTC marketcap - $2,920,128,326
XLM marketcap - $2,056,064,586
DVC marketcap - $2,025,106
(using `1 BTC = ~$9,513`, `1 DVC = 1 Sat` price and 21,286,112,500 total devcoins in circulation)
Trading only using DVC/BTC pair would leave us with huge spread even if the price goes x10.
So we do need other market pairs, such as XLM/DVC. It's already available on the Stellar network, but perhaps somebody would like to see such pairs on the other exchanges.
Introducing more than one such pair on "fly-by-night" exchanges might be a "disservice" as you say, but only if there is a low volume, so that manually going through various calculations might disincentivize a potential buyer. Having high volume on all the relevant pairs would increase trust in market prices being "fair", so no need to manually checking every time if the prices match.
With that regard, Stellar seems to be more convenient because of
pathfinding.