Sony releases one million exclusives every year, & unlike Nintendo & Microsoft, they're usually not aimed at the same demographic, in the same time span you mentioned, Sony released The Last of Us & Gran Turismo 6, both excellent games to the NeoGAF demographic, while the other games appeal to different demographics, Team ICO games aren't made for everyone, they're made for a specific demographic, while Killzone is made for the dudebro demographic (it is still the best selling exclusive between XB1 & PS4), Tearaway & Puppeteer also appeal to a completely different demographic. GoW's gameplay was as solid as the other games in the series, it just had inconsequential plot, which was what made it mediocre.
If Sont went the Nintendo/MS route of consolidating their exclusives with the same demographic, I'd stop being a Sony fan & game on PC instead, I game on PS4 because Sony tends to fund quirky games that barely sell & don't appeal to the general paying demographic.
For example, Sony is the only publisher willing to fund David Cage, & currently, Until Dawn.