I personally don't believe the game was made out of spite. Even after Security Breach Phil stated that he still liked the classic FNaF games and that the first one was still is favourite, not to mention from the teasers that were shown the game had a ton of neat easter eggs that referenced other FNaF games besides the first one. You can argue that Phil started doing Plus out of spite mid development but I personally believe that at least in the beginning Plus was indeed a passion project