In DDO quicken gives you a very fast cast time and makes the cast uninteruptable. That's great as far as it goes but that's only half of how the feat is supposed to work. The cooldown timer should also be reduced as it is supposed to allow you to basically cast 2 spells (a quickened spell and a normal one) in the time you should be able to just cast a normal spell.
When quicken is active if just the generic cooldown timer applied but not the normal spell specific timer applied you would have a reasonably good approximation of the feat. That, combined with the way metamagic works in 5.0, would actually turn this into a very useful feat that actually matches the power it was intended to have.
Edit: An additional thought to those that might think this is overpowered. In PnP you pay for the quickened spell once, in DDO, because of how the enhancements work, you would actually pay twice (since you would cast 2 quickened spells instead of 1 quick and 1 regular in PnP). That means even if implimented as I suggest it would still be a little less powerful a feat than in PnP.