I disagree. Do you travel to and from work? Do you go to the grocery store or the dentist/doctor? Do you visit friends to game? Have you ever left your town, county, or state to handle some important task or attend a convention? Ever need to go find a bathroom? These are all examples of wandering which is exactly what random encounters represent.
These are highly predictable environments. The odds that the bank is going to be robbed, that your dentist is going to turn out to be a sadist who gets high on laughing gas(+1 props if you get the reference), that the toilet in the bathroom you enter will explode in a fountain of feces are quite low. Even though the odds of those things are low, they're within the realm of possibility. In the same way that wandering through a forest means you will encounter typical forest inhabitants, though most will shy away from you.
Even so, you are still wandering into the territory of the banker, the dentist, or the dreaded toilet. There are some fairly reasonable expectations you can extrapolate from this. The bank will have money, tellers, and probably loan offiers. The Dentist will have a waiting room, dental equipment, and dental assistants. The bathroom will smell bad, be dirty, and often have un-flushed toilets.
Though there is a level of unpredictability to these things, these are all still reasonable expectations based on past experiences(which assuming the forest isn't super-special/magical/unique, your party has likely been in a forest before.
Are there more extreme things that could happen? Sure, there could be someone giving birth in the bathroom, there could be someone robbing the bank, your dentist could be a sadist. Even so, these are not entirely unexpected things. Noone goes into the bank and ends up buying a rabbit, noone goes into the bathroom and drives away in a new Prius.
That dragon sometimes goes out to eat a herd of cattle or three or to burninate the country-side. The wolves you mentioned don't sit in the den waiting for deer to walk up with an "eat me" sign dangling from their necks, they wander about hunting for prey. Do the hobgoblins refuse to patrol their hard won territory? Have the Elves or Dwarves ever wanted to conduct trade with another society?
These things are not random. A dragon attack has likely occured before(dragons are long-lived buggers). Elves and hobgoblins do not just appear out of thin air, they have homes, paths, markers that indicate that they live there. These things are not random. While you may randomly generate them ahead of time, once you do something like putting hobgoblins in a forest, it's basically mandatory that there are signs of them living there, that nearby towns have heard of/been raided by them.
And yes, like you said, adventuring does have the characters wandering into the territories of all sorts of things.
Exactly. If you wander anywhere, you will likely get a good idea of what is in that area based on local information, environment, and natural markings.
The world is sadly very much not random, and while random generation can be fun, it can also be incredibly annoying when something that clearly shouldn't live in such conditions jumps out and tries to eat you. Any angry, aggressive animal in a setting where it normally should not be is usually running away from an even more angry aggressive creature. As such, if you do run into a frost wurm in a tropical jungle, you should be less concerned with the wurm, and more concerned with what sent such a creature into a totally contrary habitat.