I talked to one of the plant professors at Nebraska-Lincoln today (he did his PhD on tomatoes), he says I probably need to add potassium to my nutrient mix, as it is vital in the transfer of sugars to the fruit. Insufficient light may be a contributing factor as well.
I think the plants probably had too much nitrogen during the vegetative state, that causes them to get leggy, with overly long internodes. I will be switching to a different fertilizer mix for the next iteration of the tomato hydroponic garden and I think I'll probably reconfigure the lights as well.
But the first cycle was intended to be a learning process for me, that I'm getting some good tasting tomatoes, even if a bit small, is encouraging.