Gameplay of Transcend was rubbish in my opinion, but the story kept me going all the way to the end, even after I knew I was stuck in a Herc II with crap firepower.
Well, the appalling gameplay of Transcend is a reflection of my lack of mission design talent and is not indicative of any mutual exclusivity between gameplay and storytelling.
And yet most "classics" are deemed so because of their gameplay not their story.
Digital gaming is still a very young industry and, at least in this discussion, "classic" doesn't mean much. Narrative didn't really become a talking point in gaming until the late 90s. As far as storytelling goes, I think we're yet to see the best the format has to offer.
Besides which there are already games many would consider classics for their plot. The fact there are more classics defined by their gameplay isn't relevant - it's not a matter of numbers.