Even today many businesses and people like to move just outside of the major city where prices are lower while you can still use most of the infrastructure. In my area, you're not going to find any non-built up places any more.
Yes, businesses like to move to the outskirts, especially industrial ones. But that's the thing, they're on the outskirts of the city limit. They're not a separate town outside of the city limit.
Businesses and residents will always want to be part of the city to benefit from its infrastructure. With it being more notable for a place like Baldur's Gate that literally has a gate that can and does seal off access to the city proper.
I get that there will always be people setting up outside the city, to profit from the traffic despite their inability to enter it. But this doesn't usually turn into a full on town.
A casual gamer may have never found the grove if it was buried in a maze of forest.
Not really. Could easily have been lead by Aradin's group the same as the goblins were. Much like how approaching the Grove as it is currently implemented leads to your characters hearing their ruckus and deciding to go check it out.
Heck, you don't even necessarily need to actually encounter Aradin's group directly... A trail of scuffles and splatters of blood could serve as a guide.
It's pretty basic design to facilitate lore friendly guides for players (That doesn't involve copious amounts of yellow paint...). If it's something important to allow players to find, you can make it easy for players while maintaining the logic of it being difficult for other people who didn't have such serendipitous circumstances to aid them.
I guess any solution to travelling the map can serve to frustrate different gamer types, getting lost in a frameless pretty painting, paralysed by possibilities or endless loading times/other performance issues.
Ehh... Not really. Like, most of the issues you bring up are not really to do with map design and are more problems due to a fixation of graphical fidelity (Which can make routes blend into the background and increase the performance cost of loading)
The only real hurdle for maps is travelling fatigue. That's the core of map design challenges.
Keeping players engaged with the game while travelling is the key.
The most obvious design for this is PoI density. If there's lots of things to encounter, then travelling isn't boring because you're not sat around doing nothing for long periods of time. The caveat to this is the amount of resources it takes to incorporate scales with map size.
The other prominent design choice for this, is fast travel. Options to "Teleport" around the map so you don't actually have to travel (Or alternatives like making "World Map Travel" designs where travel between areas is done as a dotted line moving on a map over the course of a few seconds). The caveat to this is that it doesn't always fit into the lore or can feel jarring with how disconnected you feel with the world when you just zip around all willy nilly.
A somewhat popular design choice is also to make travelling fun. Stuff like having solid vehicle mechanics, or fun things like grapple hooks and gliders can make the act of travelling enjoyable so that people don't mind travelling long distances because they still have fun doing so. The caveat to this is it's hard to pull off well and is generally only really possible in ARPG's (Or actual driving games like Driver or Burnout: Paradise) where there's more control over character movement and mobility.
A lesser used design choice is also autotravel. Things like Flight Paths in World of Warcraft, the autopath mod in Skyrim, the autodrive mod turned feature in CP2077 (Along with its Metro system), Taxi's in GTA etc. The ability to select a destination and have the game do the travelling for you is a peculiar option for the challenge. Since it doesn't provide player engagement, but rather provides players a breather. They can sit back and take in their surroundings, or even step away to get a drink or go to the bathroom. The caveat is that this doesn't help people who are unwilling/unable to take a breather and can thus contribute to travelling fatigue in people who want to continue to actively be playing the game (So it's usually best implemented as a secondary/tertiary option for travel rather than the primary means of moving through the world)