What effects does the blood moon event have on the world, other than respawning monsters?
The Blood Moon has 4 main features:
1) Respawning Enemies - As you've mentioned in your question, the Blood Moon causes monsters and guardians to come back to life (including monsters and guardians in shrines). This is useful for farming enemy parts (like Lynels), but be careful of minibosses or bosses who will regain their health after the Blood Moon ends.
2) Weapon, Ingredient Respawns - Weapons, items (like ores), and enemy encampment chests will also respawn during a Blood Moon. Certain ingredients also respawn after a Blood Moon (like fruits and mushrooms), though ingredients will also respawn anyway after a few days.
3) Cooking Bonuses - After 11:30pm, and before the ending cinematic at 12am, anything cooked will automatically result in a critical success. Critical successes include:
- 3 extra hearts
- An extra yellow heart
- An extra 2/5 stamina wheel
- An extra yellow stamina wheel
- Increased effect duration
- Effect level is raised by 1
4) NPC Behaviour - Some NPC's will behave oddly during a Blood Moon (eg Hino at Dueling Peaks Stable), though it is unclear of any of this behaviour is significant in any meaningful way.
Not a guaranteed critical cook, but you do get a higher chance of getting a bonus effect. It doesn't always make sense (I.e. Cooking 5 hearty durians can yield a simmered fruit that provides 21 bonus hearts) but you can always sell those items for more too. Also, don't forget that the blood moon regenerates ores as well!