Is your raised bed sitting on ground? Can the tomato roots grow down into it? If so, then it doesn't really matter how deep the bed is. But yes, definitely too many plants in it.
TWO tomato plants would go in a 4x4. If you have another place to put them, you can carefully dig the others out, taking a root ball and the soil around it and replanting right away. When you replant, bury them deeper than they were before. But I can't imagine what kind of yard you would have where you have room for 30 tomato plants. You would need about 250 sq ft of garden space.
Your 31 plants will just all be competing with each other for sun, water, nutrients, and the plants all growing on top of each other cut down air circulation and transmit pests and diseases. They will be weak and stunted and then will be vulnerable to what ever pests and diseases come along.
Tomatoes do best with some kind of stake/cage/ trellis situation. You didn't say where you are, but at least in any kind of humid climate, tomato leaves that touch the ground or get dirt splashed up onto them, are very prone to fungal diseases. And if a tomato fruit touches the ground, it will rot. I grow mine in cages and take all the bottom branches/leaves off, so that nothing touches the ground.
Everybody loves to grow tomatoes (and there is nothing like your own garden tomatoes!
), but for many of us, with humid climates and/or short growing season, they aren't actually the easiest thing to grow. Obviously it can be done, but it takes a bit of care.
They are all 3-4 feet tall now but each "grouping" of seeds that I threw down has 3-4 large tomato plants coming out of it (in the same spot in the soil). I have 11 tomato "groupings" growing 31 tomato plants in this planter!!! I talked to someone who told me that they would not thrive under these crowded conditions (even though they look REALLY HAPPY right now). I ordered another planter (4' x 8') and am thinking I should just PULL OUT (ouch!! I'm afraid of hurting my plants that I grew from seed!!!) and transfer a lot of these tomato plants. Is the goal to have just ONE plant in a spot - not even TWO can exist together?? Any tips on transplanting?? I'm going to try to attach a picture of my current "vegetable jungle". Oh, and we do get rabbits but I haven't seen any yet. Do they wait until you have growing tomatoes to come out? I don't have it "protected" in any way. I am A TOTAL NEWBIE and am REALLY enjoying my new garden and learning as I go!!! Thank you so much for your help!! 
Kathy