Large oak trees seem to have gone back to not spawning in forest biomes after being re-implemented in a recent snapshot in response to a previous issue report. Large oak trees were not found in forest biomes across multiple test worlds. They also could not be found in extreme hills biomes. (This is less reproducible due to there being less trees in this biome to begin with.)

Perhaps a consequence of the recent fix for certain biomes not spawning, or an intended removal. No evidence of this problem in 16w04a was found in any previous issue report on this topic.

Steps to reproduce:

Create a new world in 16w04a.
Find a forest, foresthills, or extreme hills biome.
Find a lack of large oak trees?