It would completely eliminate the issue of a raw center with a cooked outside that often happens when trying to cook fish or chicken, and the meat would retain far more of it's juices.
Well, um, let's see....
-First there's the cost of the S.V. circulator
-Then there's the cost of the vacuum packaging machine--of which many smaller places don't use for it's intended purpose of packing.
-Then there's the cost of the actual vacuum bag,it ain't cheap, a good quality one is abut 60 cents
-Then there's the cost of labour--vacuuming the item.
-Then there's the fact that many health inspectors crawl all over the place when they see a S.V. rig, they want to see operating procedures for every dish, want to see recording logs for every bagged item, and recording logs for every piece of refrigeration.
If you really go back in history and look at S.V. you'll see it was developed by a Chef who wanted as little cooking weight loss as possible for his foie gras. Then the mega-institutions like hospitals and prisons jumped on it, except they called the "knacka system" and used it as a cheap way of rethermalizing meals.
Then the butchers found out they could wet age meats in the bag and get the consumer to pay for the weight loss--this really got the vacuum packing machine down in price and in place in most larger hotels and kitchens. I remember back in the '80's those machines used automotive oil and automotive oil filters, and if they weren't changed when they should, the whole kitchen got enveloped in a cloud of smoke.....
So S.V. has it's place, but for cost effectiveness, it should be used for larger items--not individual a'la carte entrees.
That,and the fact that the S.V. fad has passed it's prime.....