What are you talking about people are proving it's a choice by cutting and pasting in the original full res textures from Crysis 1. All of the textures would've been high res initially and then cut down Crytek has the original photo's it's a choice.
There are more factors that goes into a game than simply taking a photo and slapping it onto a mesh. I would not be surprised if Crysis 2 texture budget was under more constrain than Crysis. When you look at Crysis the majority of the scene people praise and accolade is covered with just a few textures. Vegetation is the most dominant feature in Crysis and the all those vegetation are just replicas spread across the terrain. There is more texture variety in Crysis 2 and when their is more variety there is a need for more textures which can increase the number of textures used. In a nutshell, Crysis had a greater opportunity to have higher res textures for certain application because of the scene than Crysis 2. I am basing this on my experience in texturing and lighting environments.
My statement is based on the fact that people have already imported higher res textures from C1 into C2 and it runs fine (it's been done! Do you not understand?). You can't argue with me just because you mess around on blender, or even if you worked on Avataar a fact is a fact. You can't use experience in lighting and texturing to unprove a fact.
Plus if you want to be literal I have experience (a month)in lighting and texturing scenes as well in Blender. I wouldn't say it helps or hinders my argument at all. Still image are not games but facts are facts and people are saying you can cut and paste them in.
PS: My experience is that, in terms of STILL IMAGES at least, when dealing with flat surfaces like walls or other simple shapes like cylinders that it very much is a case of taking a photo and slapping it onto a mesh. Maybe adjusting the scale or orientation sometimes. See here.
http://asitssfl01.ase.tufts.edu/blackboard/DR21/ImageTextures.html
What is it you have been doing to suggest otherwise? I'm interested in learning about it.
I think the level of the budget may be the choice we are discussing.
Here are some textures I slapped on to a mesh to prove my point regarding a still image in Blender.
http://i36.photobucket.com/albums/e35/Acerimmer1/Untitled.png
from what I know about it I would imagine that they have high res textures on file somewhere (after all given that they reused textures from C1 on C2 it makes sense to have high res from C2 on file in case they're needed for some future Crysis release on PS4 and X Box 720) and that a small number of Crytek staff could most likely knock up a high res texture pack in very little time at all with one arm tied to a chair. If not by some automated process in Cryengine 3 or improvised.
You do realise that consistent and playable framerates are very important for gaming. I can use 8k or 12K textures on a model in Maya or Max without any problems because the final results is NOT for real-time. When any game is using textures, models, effects etc there is a memory budget. Yes you can easily slap an unedited high res texture into the game but at what cost? ALL game developers pay attention to the memory budget and try to balance quality with performance. And this idea that Crysis only sported high res textures is nothing short of nonsense. But I guess its easier to ignore the overall texture complexity in Crysis 2 to that of Crysis.

Not everyone has a system that can run all high res textures and this was the very reason Crysis had MODS that sported high res textures. When was the last time Crytek released a high res texture pack? Again don't conveniently forget the that Crysis sported less variation of texture to that of Crysis 2 and the majority of the the scene were instances.