Is dry rub necessary in making bbq ribs?

Your ribs will have a lot less flavor if you do not use a dry rub. However you can minimize some of the time (and only a bit of the flavor) by putting on the rub, wrapping in foil, and immediately putting them in the oven or on the grill. The process of putting your rub together probably takes only about 5 minutes - it's the fridge time that takes a while.

Sitting in the fridge allows some of the flavors to permeate, and if you used a more permeable material could allow your ribs to air out a bit. These are good things, but for my rib recipe I don't put the ribs in the fridge and they still taste great. I also don't put the barbecue sauce on until about the last 20 minutes of oven time, when the foil comes off and the sauce goes on. Until then the ribs stay in the foil.

I looked up North Carolina (which uses a sauce that isn't tomato based in the eastern part of the state), South Carolina (a mustard sauce), Texas, Memphis (which uses no sauce), Kansas City (tomato based-sauce that is rather sweet) - all of them used a dry rub even with wide variations on the sauce and for both beef and pork ribs.

You can certainly do without the rub before hand. Keep in mind though that one of the functions of marinating in an acidic wet rub will be to break down the connective tissues. Going straight to the grill without a marinating wont be as tender. One alternative is to cook the ribs in a slow cooker full of sauce all day while you are at work. This will cut down on the planning and result in a fall-off-the-bone outcome.

For traditional BBQ (low and slow), dry rub does tend to add quite a bit to the flavour. However, you do not need to leave it on that long. As a matter of fact, if your rub has a lot of salt in it, leaving it on that long will result in ribs that are "hammy" (almost cured like ham or pastrami).

You'll notice after 5-10 minutes of putting on rub that the salt has been sucked into the ribs along with some moisture (they'll get a clammy look). That's long enough.

With regards to saucing, always glaze at the very end. If you like the sauce baked in a little, put them back in for 5-10 minutes, but keep an eye on them. If the temperature is too high, sauce with a high sugar content will burn. My personal preference is a really thin glaze (or none at all) and sauce on the side. Let the meat speak for itself instead of masking it with sauce, as way too many people do.

There are other ways to keep your meat from drying out while it tenderizes, but the rub is just so darn delicious.

You could probably get away with BBQ sauce only, but it would definitely not be as robust a flavor. A marinade would get you there in the flavor department. I had Coca-Cola marinated babybacks once, and they were outstanding.

Or you could try putting ribs in oven immediately or shortly after applying the rub. A salty rub can begin curing your meat, which would result in a bit of a "hammy" taste to the ribs. I'd say, before anything else, do what you normally do except change the amount of time the ribs sit with the rub on them. This may be enough to get you past your prep time objections, and you're only changing one variable at a time.

For most smoked/BBQ/low-slow meats, a brining or marinating process with liquid is indicated, and the dry rub is applied just before the smoking/cooking process begins. You could try vinegar, apple cider (I love that one), watered-down beer, etc. I've made my own marinades from combinations also; vinegar and water with Worchestershire, "liquid smoke", and Tabasco works pretty well on some things, including ribs.

I've had great success with this wet marinade/dry rub approach.