The problem with the carveouts that utilitarian vegans make for honey is that they're largely falsifiable feel-good apologia. The claim that harvesting honey doesn't harm bees is complete bollocks, really it's in the same realm of the claim that milking a cow doesn't harm the cow because she can always make more and just saying it isn't doesn't make it so. The hive does need to downsize and drones do have to die to accommodate the loss of surplus, workers do forage further and compete more with other insects for nectar, while honey harvesting rarely harvests at the low extraction levels claimed to be harmless and domesticated bee colonies crowd out native pollinators. If it were harmless the bees would never bother to make it, it takes a shitload of energy for them to produce it. It's turn-brain-off dissonance territory in the same league as dairy farm propaganda but because vegan utilitarian thought leader Peter Singer said it's OK they're all willing to make the huge leap in logic to eat something that could just as easily have been maple syrup or agave nectar.

I'd respect the utilitarians a lot more if they just said they don't care about bees and shellfish because they're not fuzzy mammals, instead of performing these unimpressive acts of logical acrobatics.

Also to add another reason for veganism to your list, the more important one for me personally: The reflection on oneself. We are symbolic thinkers, we transpose ideas from one context to the next. eg Slaughterhouse workers exhibit the same elevated levels of domestic violence as cops. When we harm someone else, in another manner we also harm ourselves. If we can understand another entity on some level and we then hurt it, we do ourselves a psychic injury that isn't just philosophical but has real profound effects on our thought processes, our outlook on the world, our behaviors toward other things. Maybe utilitarian vegans just don't see any commonality between their bodies and the beehive, but I think the core failure of utilitarianism is it's inability to respect this very simple but unfortunately intangible concept, in all contexts.