http://gamingbolt.com/wp-content/gallery/10-gaming-forests/far_cry05.jpgVegetation in DOOM 3 looks similar to that (a little worse becase they baked AO in to the vertices) no shadows, no AO, surface material/texture seems OK, but it doesn't look grounded. Just to be sure I wasn't going crazy I asked 26 people in the office, and they all agreed it needs AO and shadowmaps at least.
http://www.narby.net/img/ce2_tutorial/v7.jpgWith some AO and shadow maps vegetation could look astounding. Even with mediocre content.
AO is used to ground things, it's pretty much a standard. There is a reason why those features exist, because if they didn't we'd have unsatisfactory looking vegetation is almost every game.
Alpha blending was achieved to some degree by using edge dithering, which gave vegetation in Quakewars a soft look. We also baked the AO in to the megatexture, to ground it.
In regards making vegetation the "Crytek way" it's common knowledge, there are a tonne of articles out there using the same technique.