At this point I think that long and short resting should be limited, or rather discouraged, by both Random Encounters done well, and by food and drink. They should also be limited by location. These are probably the easiest implementations that they could do with minimal work involved.
And I would like to see them either incorporate the current mini camps on to the game map or just get rid of those completely and have resting areas that are already on the map as we've already discussed.
As Max said, Random Encounters and food and drink if done well would not really limit long rest spamming, but it would discourage it. If you know that you could potentially get attacked by yet another Goblin party on your way back to a safe zone, you might risk shutting the door in the Goblin base where you just rescued Halsin. You might risk setting a watch and then doing a short rest to just recover some of your resources enough to maybe continue on to fight the goblin leaders. If you shut the door inside one of those areas, you know the risk of a random encounter will be lower than if you try to risk fast travel back to The Grove. It makes you think and have to try to decide what risk is greater.
And the food was more limited, not so much so that it frustrates players, it also creates this idea in your head that you would better be careful about how much you actually long rest. You might search around for food a whole lot more. Having more of a scarce food supply would also add value to the ranger class. They could then use their survival skill with advantage in their favorite terrain to forage for food. Thus rangers wouldn't have to worry as much as other classes about food shortages. Druids could also use goodberry to not have to worry about food as much. These kind of things have no value currently because you can find so much food that you can rest forever and never run out.
As for location, I thought it was a really good idea that you should not be able to rest until you have unlocked either a fast travel point or a camp. If you drop down into the underdark, you shouldn't be able to fast travel to camp until you found one of these things. Likewise, in the beginning, you shouldn't be able to Long rest until you find a camp beyond the nautiloid.
As for short rest, I still think that they should also be discouraged more by the same type of elements. There should be a lesser food requirement, a chance for Random Encounters, but as far as location, I think that you should be able to short rest anywhere. I'm still on the fence about limiting short rests to only two per day. Allowing characters to take more short rests encourages using them more than doing a long rest.
My point about short rest is that right now they are hard limiting it to only two per day. I'd like to see them lift that hard limiting and apply the same concept as long rest except that short rests cost a whole lot less than long rests and are less risky. Maybe the food cost for a long rest is 10 times that of a short rest and the risk of a random encounter in a dangerous place for a short rest is like 1/10th the chance of a long rest. So you could do a short rest in a hostile Goblin camp with the door shut to the room you're in, and it would only be like a 5% chance of a random encounter and like 10 food. Meanwhile, if you try to Long rest in the same place, it would be a hundred food and like 50% chance of being caught by a random encounter.