Back to the OPs question. Talking newer used trucks here. Leaving out the engine reliability discussion.
A used 2wd truck is a great economical choice due to its same on-road capabilities in general, combined with their lack of popularity should apples to apples net you at least 2x the savings as the initial 4wd upcharge. At least that's what I see for 2 wheelers.
No other downsides other than off road/bad weather, both of which can be mostly avoided if one is retired/not on a schedule.
Regarding traction and 2 wheelers, there's a few things that can be done to maximize what ya got.
1. Get one with a locker if possible. GM G80 or Ford e locker. At a minimum get limited slip.
2. Know how to get more out of a posi or limited slip by using your parking brake to get he other wheel pulling some in slippery conditions. (Not in the hiway, think wet grass or mud pullout scenario).
3. Tires. If you're going to get into anything sketchy, run some good AT tires at least on the rear. New highway donuts on your truck? Have them siped right away. Will take a little life span out of them but incrementally better traction on wet/icy roads. Wiping won't help with the wet grass scenario. Best traction = skinny siped mudders.
4. Moving up the sketchy ladder to driving/towing in snow and ice and mud. All of the above plus a set of chains = instant traction.
5. Tire pressure. On the dry hiway, who cares. Tire wear is your only enemy. Slick or off road? Know when and how Much to air down. Yes it's a pain to air back up. Easier than sitting in the ditch though.
6. External traction aids. Cheap and easy to bring along. Couple good lengths of some heavy orange construction fence (not the cheap Home Depot stuff) and a few steel or wood stakes make great traction mats for the wet grass, muddy lot scenarios. If you want to get crazy chain link works well too.
7. Steering. I wouldn't run a 2 wheeler anywhere sketchy without the same good traction tires up front. If you're just worried about the wet grass skip this. If you may get a little more western than that, have good front tires too. Same rules as back tires.
8. Driving style and traction control. If you don't know how to drive, you'll get stuck or spin out 10x more. See 3-6 above for some help. Otherwise go get you some experience in a controlled environment. DO donuts in a snowy parking lot til you can drive like Bo Duke!
General rules.
Don't stop moving. If it's slick keep your momentum.
Try not to spin tires liek a madman.
Turn off traction and stability control, Before you need to giver the beans! Yes it can save you from spinning out. (See donuts comment) but it will also keep you from moving when you're on the verge of no traction and won't let you spin the tires when you need to.
One can outfit themselves (skill) and the vehicle to go a lot of places that most would just flip the switch to 4wd, just have to know what to do when you get into that situation, preferably before.