Well to me, there is a certain attraction for all discontinued fragrances but only for research purposes, and only slightly if it'll catch my eye to be in my personal collection, unless it's either very very rare or if it's from a house i find particularly exciting.
But in general, if i get my hands on a fragrance that's been discontinued and that i do not know how it smells like, and then smell it and it basically doesn't particularly lure my senses, then that attraction might die -instantly.
About some of the scents that seem to be discontinued, when a house decides that it's not going to ship or distribute a certain scent in a certain country (or continent) then it can be said of that scent that, for all practical purposes that it's discontinued.
But that's not always the case: a certain scent that it's not shipped to the USA for example, might still be in production in, say, a very small city, or only in a certain country (like for example fendi's Theorema for women). And then some vendors might consider that certain scent as discontinued, when in reality, it's not.
It's all relative.