I think it's really about an individual's palate and/or how deeply they want to get involved in the hobby. Kits have their advantages such as they require only minimal equipment, can be made anytime of the year and are great for someone getting their feet wet in the hobby. However it's not quite that simple since kits are of varying qualities.
I've not made a kit since my first year in making wine so I had to look at the current pricing. From what I find, and I'm sure there are sales to take advantage of, kits range from just over $100.00 to just under $300.00. If I were to pay $1.75 per lb for grapes which is slightly above average, it would cost me under $200.00 to make over 6 gallons, probably closer to 7 gallons depending on the varietal. A juice bucket if you have a source is under $70.00 but is typically seasonal. Both grape and juice bucket wines are economical but do require differing amounts of equipment and supplies.
In my opinion processing the juice for white wines is similar for grape, juice buckets or kits. The grapes are crushed and pressed to extract the juice. I'm not exactly sure the process for concentrating the juice for kits is so I can't comment on that. However, should I press juice from white grapes it takes me over 100 lbs to get 6 gallons which is about $150.00 as opposed to $70.00 for the juice bucket. I realize a commercial operation is probably more efficient than mine at extracting juice but not over twice as efficient so I have to question if it is all juice and not watered down. Now the explanation could be warehousing and shipping though they both require refrigeration and I have never had a juice bucket that hadn't already starting fermenting.
I'm sure there are techniques for processing red grapes which I don't know about. I just can't wrap my head around how they can get the color, tannins, phenols, etc. from a quick press and processing with maceration. Although reds from grapes do yield a higher volume when I ferment them it is still not to the volume per lb as a juice bucket. Plus, whether red or white, why do juice bucket producers insist on adding yeast in the first place.
Now more specific to kits. Again, for whites the process is similar and although I don't do them I would think they would be close to wines made from grapes. Most all commercial reds go through MLF which evidently kits can't or are not supposed to go through because they are balanced. But what are they balancing and to whose palate. Is it acid to alcohol, sugar to acid, alcohol to sugar or a combination of all. Plus not going through MFL there is a high content of malic and no lactic which will not have the same characteristics of a commercial wine and in my opinion contributes to the kit taste. In most posts I read it appears kit taste is not as noticeable in white kit wine which in the commercial world does not typically go through MLF.
Again palates are different so it's a matter of what you like. It's fairly common knowledge people new to wine prefer a sweeter wine. Whites are less tannic than reds so this could be why some prefer whites over reds. There are so many variables so the important thing is to make what you like.