Actually, your cake mix referece is apt. I work in the food industry, and
General Mills has done extensive research into this. There's a bit of a tug
of war between today's push for convenience as well as the desire to
'cook from scratch'. the mixes are designed such that both desires are
fulfilled - you can do them quickly, get a very high quality result, and
you're still cracking the eggs yourself and doing all the mixing, so it very
much satisfies the need for the scratch cooker, whether or not they
consciously recognize it.
Granted, they're not going to meet the needs of 100% - you'll likely not
find pastry chefs doing this, but then again pastry chef's aren't the target
demographic, and they represent a very small portion of the population.
At the end of the day, if you do it, it's because you find it interesting,
relaxing, and/or you're satisfied with the outcome. If you're a purist
you'll spend a few million on land in california, plant your own grapes,
attend a viticulture series at UC Davis, and the rest of your life learning
how to do it all on your own. The beauty of the kit options is that you
don't have to do that, and (apparently - mine aren't done yet), can achieve
comparable results, while keeping your day job.
I'm a bit of a skeptic myself - my advice to you is to find a local brew
group and offer to trade something for a taste of one of their high end,
aged, appropriately made kit wines. That'll give you a feel for if you want
to spend money to enter this hobby, as you'll be able to guage the
outcome of a well done product yourself. I understand there's a home
wine expo in baltimore this august as well, and have been encouraged to
attend - you may wish to consider that.