From what I understand worms contain alot of nutritional value that frozen foods do not provide. Things like Vitaman K are easily lost during processing and freezing process, while the worms that naturally filter feed on the dirt packed full of nutrients, will have more fresh nutrients.
I know that it is important to keep your worm farm fresh with new nutrient enriched soil, and even consider feeding them or 'gut-loading' the worms with a specific food.
Keep in mind most nutrients are water soluble and will lose their nutritional value quickly when submersed.. that is why soaking massivore pellets to soften them up is great for texture, but bad for nutrition..
Live Worms is probably the best live food you can feed them.. Goldfish have thiaminase in them which make the consuming predator Vitamin B1 deficient.. that's bad. Ghost Shrimp and the like are great enticers, but hold little nutritional value. Prepared Seafoods are great fillers and a great source of protein, but the thawing process voids most nutritional content, so seafoods need to be fed with variety in order to meet nutritional needs..
just my 2 cents..