It's been pointed out in the thread about those screenshots that the plants in the image don't really look that much better than Oblivion,
Since there are no mammoths or giants in Oblivion, here's a scenery comparison.
http://i.imgur.com/gGHUa.jpg
That seems like a pretty good comparison, it definitely puts the visual differences between the games into perspective, and I'm inclined to agree that the grass doesn't look that great, though this problem was present in other screenshots that showed grass as well, so it's not really a new thing, aside from that and the textures on the mommoth looking a little low resolution, though, I was fairly pleased with the screenshot, and really, those are the problems I'd expect to see due to the limitations of console hardware.
Dude, we have no idea when that pic is from. Bethesda randomly decided to release it. It could be from early tests, it could be while running a test on low settings. We just have no idea. Chill your boots, kid. TES was never about graphics and never will be. This isn't Uncharted 3 or even RAGE. It's a huuuuuge game and thus you have to sacrifice some graphics.
And yet both Morrowind and Oblivion were considered pretty graphically impressive when they were released, the reason why the graphics are not top of the line is not because of the kind of game it is or that Bethesda isn't focusing on that aspect of the game, it's that they're constrained by five year old hardware. Still, I can certainly live with the graphics as they are now, it's not like I expected Skyrim to be the next Crysis, but saying that graphics were never a major focus of the series is simply not true.
Its a single frame. All screenshots are like that. When your playing it will look much better when your seeing 30 frames per second.
Actually, that's not always true, for one thing, screenshots don't capture animations, so it may be that seeing the game in motion will actually make it look worse if the animations are bad, further, when playing the game, you get to examine things more closely and from different angles, potentially noticing flaws not visible in the screenshots, of course, it may also be that while playing the game, you're focused on, well, playing, rather than looking for every flaw you can find in its graphics, so in the end, it just depends.