Essentially this is what happened/is happening with scenarios;
Scenarios revealed: Cool, short, story driven instances where you can queue instantly without regard for tanks or healers.
What actually happened: Short instances with instant queues, no good delivery on any story elements and no gear.
What happened in 5.1: Good, story related instant queues that give valor.
Now, between launch and 5.1, Blizzard has apparently realized that people WANT story in their scenarios. This seems like a no brainer given that they were initially advertised as being just that; short instances that progressed the Horde/Alliance war across Azeroth. *That* has only just started in them, but what we have is pretty good. Far greater than the first batch of scenarios was. Plus, they do still give valor.
Wasted dev time? I wouldn't say that. Even the launch set serves the purpose of getting players points. However, I do openly admit that I *wanted* story in them from the start. However, MMO development is very much an organic, living process. They will NEVER score a homerun on every single feature added from day 1.