Can you be more specific? In what technical level Far Cry 4 is far superior to Crysis? Because I think it's completely false talk of technical level here.
Farcry 4 uses a physically based renderer, Crysis does not. This automatically means Farcry 4 has better lighting. It also has GI and it's real time, Crysis has no GI at all. Crysis was the first game to use SSAO so the implementation is extremely rough, FC4 uses HBAO+ on PC and something close to that on consoles. The world is much bigger, the draw distance is much higher too, vegetation is considerably more denser and the vegetation animation is far superior too. There's also a fire propagation system in place. Better shadows, better character models, better textures, better materials. One of the most persistent smoke and fog effects seen in games, something which Crysis lacks, also higher quality explosions. All in all superior alpha effects. The post processing is superior too, only thing Farcry 4 pares back on is the object motion blur, Crysis is very liberal with it while Farcry 4 isn't.
It's been 7 years since Crysis 1 came out, rendering tech has progressed considerably since then with more refinements and invention of new techniques. It'd be wrong to claim Crysis 1 was superior to Farcry 4 technically. Crysis 1 is ancient tech now.
On a technical level Far Cry is superior in that it uses Deferred Rendering (and even supports MSAA) without visible sacrifice. Yes it has PBR, but that is more of a change in shader math than any real technical feature (although it's not trivial to implement, not saying that). For most of the open world sun-only gameplay it is probably the more expensive solution, but since FC4 needs some more lights it's right to say it's the better solution overall.
Far Cry does use all the stuff that over the years successors of Crysis 1 (and others) introduced and are now state of the art, like SMAA, Screen Space Reflections, Screen Space Subsurface Scattering etc.
Other things that Far Cry does better: has bokeh DOF.
Has working AA for alpha textures (Crysis had some early edge AA, but did not help too much with the palm leaves).
HDAO and the stuff Nvidia is pushing like better godrays etc. are neat and also better than Crysis' counterpart. More info and overall comparison pictures for graphics details in FC4 are here:
http://www.geforce.com/whats-new/guides/far-cry-4-graphics-performance-and-tweaking-guide
What is relatively unique in Far Cry is the fur rendering which i haven't seen in other games plus the fire propagation as said.
Unique is the precomputed global illumination solution, though it should be noted that Crysis also has precomputed ambient occlusion.
Crysis has POM on almost all ground textures, a thing that I have not seen from Far Cry 4 at all.
Crysis has detail textures (secondary small tiling details) on basically all materials, Far Cry 4 does not (big thing)
Crysis has subsurface scattering with translucency maps for human bodies and ice, something new games are returning to in combination with the screen space solution.
The water in Crysis obviously looks a million times better but only when comparing Crysis Ocean with the lakes in FC4. Crysis lakes had no real time reflections.
I have no idea what the creators were thinking in Fc4 though... ?!
http://a.pomf.se/vebzuz.webm
This video posted... holy shit. This looks like a 2005 tech demo. Water is really shitty here. Like a plastic plane. wtf.
To the guy which said he remembers Crysis to be better looking. For some parts this is definitely true, subjectively. The webms posted do not look very good in my eyes, this is more appealing (maybe a bit nostalgia lol)
https://www.youtube.com/watch?v=5ViG_uWeUEk
And the ingame models of characters ... i don't know i find it hard to argue that they are in general better than in Crysis 1. Of course Crysis 1 only had a few of those overall but yeah...
everyone who played Crysis will acknowledge that character quality during ingame cinematics and gameplay is not really lower on major characters than that.
On the other hand I'd argue that this simply looks worse and here we also have a major character during the first seconds of Far Cry 4.
So for some parts Crysis definitely holds up. But overall the flatness of the world in terms of colors is really a problem in many other areas. Far Cry 4 is much more consistent. It has undeniably more colorfull palettes and the shading is never as flat.
Far Cry 4 is definitely better in terms of amount of features and efficiency as well as visual impact of these features. It is clearly technically superior, but the difference is not as big as 7 years would suggest.