And effort, in my opinion, isn't enough to justify eating animals. Think about the specific efforts you go through to prepare raw chicken: you have to wash your hands in between handling it and your other foods so you don't risk contaminating them with salmonella. Way more effort than my dinner, where everything can safely touch!
Iron is more difficult in theory, but no other vegetarians I know have actually had a problem with it.
[1] http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2621.2002....
Additionally, the only vital nutrients in meat are b12 and iron, both of which are available elsewhere (lentils are great for iron & supplement is available for b12)
Apart from that, I would cede to your points about the b12 and iron, but if you want calories to sustain you, meat is definitively the most efficient way to go about it.
I make a vegan sandwich with 30g of protein and about 700 calories. Add a protein shake and a side of chickpeas and you're pushing 90g. It's shockingly easy (and healthy) to load up on vegan calories if that's your goal!
Point being, meat is the most efficient way to get a lot of nutrients, and you can't declare that everyone can't eat it because you may someday discover that it's intelligent. The future is broad, we might find out that plants are actually the intelligent beings on this planet. Does that mean we should all starve ourselves now on the fear that that may happen in the future?