The 2WD 'Runner still has great ground clearance, and you can put good tires on, and still do decent off-road. Better than any car. And if the most you're likely to encounter is gravel/forest roads, well, you don't need 4WD for that.
The bigger issue here is getting talked into something you didn't really want. That sucks. If you can somehow take the truck back, you should maybe look into it, because you don't want to be kicking yourself in the pants every time you have to make a payment on the thing. My advice is to never buy a car when you need one badly, and to decide exactly what you want beforehand, and be willing to put in a special order and wait for it. I do this with all my vehicles (although sometimes I still find myself regretful for not ticking off a certain option box when I had the choice, lol - it's just human nature to play "what if?" sometimes, but you can't let it get you down too much).
When I bought my truck, I knew what I wanted before I talked to a dealer: SR5 Premium 4x4, Black on Sand Beige, w/ 3rd Row Seating and Rigid Running Boards. There aren't too many options on the 4Runner, the way everything is broken down into trim levels and bundled, but I still thought my choices were pretty specific and that I was unlikely to just stumble upon a 4Runner configured exactly that way. I did some test drives, and talked to a few sales guys about putting in an order. Of course, they tried to sell me their inventory. You can't let them do that. If I'm paying a premium for a new vehicle, it's gotta be exactly what I want (my favorite is when I was shopping for a specific manual transmission car and the guys kept trying to sell me autos, even after I told them the manual transmission was non-negotiable - all these guys care about is making a sale today!). Anyway, the sales guys jerked me around a bit, thought I wasn't "serious" even though I was willing to put a deposit down on an order and wait, and then the exact truck I wanted, minus the running boards, popped up at a dealer half a mile from my house. So I jumped on it. I found out afterwards that those specific running boards weren't sold as an accessory by Toyota, which was a little irritating, but I was able to find them secondhand from a member here.
Sorry for the long story. The point is, always remember you're the one on the hook with the bank, so buy what you want. If you can take the 2WD back, maybe you should, if only to make yourself feel better. Otherwise, you can be pretty confident that you likely won't need it unless you go looking for a reason to. Finally, pat yourself on the back for all the money you saved. It's not like 4WD is free.
And Toyotas in general enjoy great resale value, 4Runners in particular. It may not command the same price as a 4WD version on the used market, but your upfront costs were less, too. So I wouldn't let that bother you too much. Especially in certain markets (TX, FL) where a lot of buyers are specifically looking for 2WD trucks.
gotta make the educated decision by yourself and think realistically what you're going to do with it. My two cents for whatever it's worth.
