I think you have absolutely no idea what you are talking about… Metal Gear Solid 5 is developed on the Fox Engine, It’s the same engine P.T was developed with. They don’t have just a Directional and Skylight, they also have a very good GI solution basically they are also using light probes.
Left side, just directional and sky light. Right side, generated cube map for GI and light bouncing / indirect light.
The same goes for the Witcher 3 and all the other games, all of them are using some kind of GI and indirect lighting, no matter if probes or fully dynamic GI. A game developed only with the power of a directional and sky light, will have no GI, will have no indirect lighting / bouncing… as a result it wont look good.
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That image comparision is flawed. Left one is directional sun light only. Right one have also ambient cube + captured skylight. With ue4 you could use movable directional light combined with stationary skylight. This would allow sky to have occlusion baked. Then you just can recapture skylight and tint GI from skylight to have time of day effect like Metal gear solid have.