Cleaner waxes definitely have their place in the pantheon of products, even at an Autopian level. Some of the most respected products here have cleaning ability.
What you will learn is that once you have the paint the way it is supposed to be, the work turns from correcting the finish to maintaining the finish. Your work turns to preventing swirls and spiderwebs, and keeping your paint and finish mar-free.
The most common use for a cleaner wax is to maintain appearance throughout the season without multiple steps. It will remove minor contaminants but not address paint defects, while putting down a layer of protection.
Cleaner waxes are not a substitute for the PC, 5 steps, and elbow grease, but they will help you extend the time between those sessions.
Don't confuse them with waxes that have some cleaning ability, noticeably much of the Meguiar's line; Gold Class, NXT, Medallion, #20... this is part of a corporate belief that a little cleaning ability improves the results. It is a perfectly good philosophy that works for some users and not for others; both beliefs work quite well when implemented properly. A true cleaner wax is labelled "Cleaner Wax". Waxes with cleaning ability only work well on prepared surfaces, they don't clean enough to remove average oxidation and surface contaminants.
Many of us prefer 100% non-cleaning waxes and sealants. I try to use them myself as much as possible on my vanity car, which is garage kept, washed every other day, and waxed frequently. For my other cars, a once a year 5 step with monthly cleaner wax is the way I go.
My favorite cleaner wax is ColorX, followed by the regular Meg's Cleaner wax, Mother's Cal Gold, and Meg's #6.
Tom