It is absolutely worth adding ground pork or veal. I usually use a leaner ground steak and compensate with a fatty ground pork (shoulder is good) - fat = flavour.

Another tip is to take your time. Many people try and cook bolognese in half an hour, but considering ground meat is usually made with tougher cuts, you end up with tough meat and under-developed flavours. Use plenty of onions and garlic, brown your meat well, use good wine, stock, tomatoes and herbs (thyme, rosemary and bay) and gently simmer that bad boy for at least 3 hours. For ultimate flavour, cook it the day before and let the flavours marry overnight.

In the British tv series "In Search of Perfection" with Heston Blumenthal, Heston visits a chef in Italy that makes ragu bolognese with whole pieces of meat that are braised and then shredded. He comes up with a combination of pork and beef cut into larger chunks and cooked for a very long time instead of using ground meat. You might want to try a similar approach.

From the recipe for ragù (what the Bolognese call their meat sauce) in Essentials of Classic Italian Cooking by Marcella Hazan:

The meat should not be from too lean a cut; the more marbled it is, the sweeter the ragù will be. The most desirable cut of beef is the neck portion of the chuck.

The recipe calls for no less than 3 hours of simmering as well! Maybe you will be more pleased with the result by following the same classic recipe.

Stop using ground meat. It's too lean, lean meat cooks fast and then dries out..period. The only way to pull it off is to cook the sauce separately without the meat...brown the meat until it's just cooked and stir in the sauce.... STOP right there.

Alternatively use "sausage grind", this is meat ground for sausage that hasn't been made into sausage yet.

But if you want good bolognese, use slow cooked parts like beef short ribs, pork shoulder (picnic roast will work) and / or veal breast or veal osso bucco. Slow cook the meats separately until almost done, de-fat the juices and reduce the juices until slightly thickened. Make your sauce and finish cooking the meats in the sauce slowly...add the reduced juices for more flavor.

forget about ground meat bolognese

I think the beauty of Italian cooking is in it's simplicity. Most classic recipes have fewer ingredients than you think and for good reason. The quality and freshness of those ingredients are key, but more is not better. If you want the meat to shine use a marbled cut (eg neck portion of Chuck) and add milk to the meat / vegetable mixture while cooking for sweetness. As for all the the herb and spice recommendations, i'm not a fan. Again the classic Bolognese Ragu is seasoned only with Nutmeg, salt and pepper - not even any garlic. Also, with regard to other meats, i say "yes", but to meat mixtures, I say "no". Tuscan versions often use wild boar which is great. I'd say any richly-marbled cut of your favorite meat will make a nice ragu, but don't trouble yourself with meat mixtures or exotic, labor-intensive cooking processes. Simple & less always yields the best result for this dish.

If your meat sauce is dry it suggests you have other issues - Are you adding enough liquid? For a pound of meat I would be using a can of chopped tomatoes, some water/beef stock (as required), some milk (a dash) and some red wine (1/2 to 1 glass)

What kind of meat are you using? What % fat is it? If you are using e.g. ground rump then there may not be enough fat. One solution is using a more fatty cut or as you suggest add something like pork/veal. My butcher usually has 2 types, either ground beef (usually 15-20% fat) or the more expensive steak mince (5-10% fat). I use ground beef for most things except a few pies which I dont like too fatty.

First I must agree with @ElendilTheTall, He is completely correct that it is worth adding pork, I would also suggest some ground lamb. Then on one of those 'other' evenings, when you might be 'into' doing some cooking use the ground beef, pork and lamb to make meatballs.Season them with some oregano, paprika (and other seasoning, to taste), add dried bread crumbs, along with two eggs. You can then freeze the meatballs and add them to your bolognese for a rich juicy meat to go with your sauce when you need a quick/simple meal.

I’ve found that dried bacon chunks work nicely.

When I cook pasta, the typical recipe I use is a packet of pasta (four serves), a jar of bolognese sauce (four serves), and a generous pouring of shredded dried bacon - typically from Costco because it’s the only supermarket that seems to sell it in Australia.

Once the sauce starts making bubbling noises, I take it off the stove serve up the portions for the night and stick whatever is left over in the fridge for subsequent nights - a minute in the microwave is often enough to get it back to an edible temperature.

I’ve found that the bacon bits add a very nice smoky flavour to the pasta sauce, and they have a nice texture that contrasts well with the pasta and the sauce. Plus, it’s fast and easy to make - there’s no need to spend lots of time preparing the ingredients, since everything comes right out of jars or plastic bags.