The reason there's topics about voice acting and gnereal suggestions is because we want to get our opinions out before it's too late. A lot of these ideas are about gameplay (although a lot are awful), and must be added into the engine before design.
That's true, though I suspect that, if the game is in development, it might already be too late to make major changes to the core gameplay mechanics, though since we don't even know if it's in development or not, I can't say that for certain. I'd imagine that the basic engine and core gameplay would need to be completed before they could get to things like designing quests and locations.
But regardless, since the game has yet to be announced, it's impossible to say how far it is in development, but if Bethesda isn't ready to announce it yet, that probably means it can't be in any condition to be ready for release, I believe. So yes, we need to wait, how long should we wait? I don't know, but we can't expect to get the game now.
Now, I want another Elder Scrolls game as much as anyone, but I can wait, there are other things I can do with my time while I wait, such as play other games. And I realize that if Bethesda rushes to release the game before it's ready, the end result will, at best, be game that's incomplete but still entertaining, and suffers from many bugs, unpolished game design, and maybe even content that was cut because there wasn't enough time to finish it. It could also end up having all the bad things I mentioned but also fail to entertain. So I'd rather Bethesda take whatever time is needed to produce a game that will be satisfactory to players. Now, I also realize that Bethesda can't delay the game indefinately, nor would I want to, the developers need to, at some point, just decide that they want something specific in the game and go with it, sure, maybe there are ways in which the game isn't quite as good as other games, but if the developers keep trying to add more to the game, without settling on a plan and sticking with it, and don't release it, we get something like Duke Nukem Forever, so Bethesda still needs to release the game, they should just what time is needed to ensure that when it is released, it won't dissappoint.
I do hope we at least get an announcement soon, though, I can wait for the game, but it would be nice to at least get some assurance that the Elder Scrolls series is still going.