Before the first expansion, the human city in WoW - Stormwind - reachable at level 1, contained a black dragon and their minions that could potentially appear and kill any low level character in the castle at the time. Higher level elites than most mobs prowled the Silverpine woods in the Sons of Aragul. Multiple zones had sub-zones containing higher level or elite enemies. Giants in Aszhara or the entrance to Uldam in Tanaris. What you describe is literally how WoW was designed at launch.
-edit and this should really come as a surprise to no-one, as WoW like Everquest before it derived a lot of it's design principles from fairly old-school D&D.
Yep! A huge part of WoW improving its reception by gamers generally was by moving away from old-school-D&D design, and WoW itself
was a stepping away from the intensely punitive old-school D&D design of EQ.
My late father absolutely adored EQ--but he really,
really disliked some of the ways that it could be needlessly obtuse, punitive, and inconsistent. When he eventually switched over to WoW, he loved it too, and very much appreciated the ways that they'd cleaned things up, made things more consistent (note:
more consistent, it's very relative).
But, by that same token, I am a pretty big advocate against
excessive motion in that direction. Something video game developers learned in the late 00s/early 10s was the correct lesson that games of the preceding decade (in particular RPGs, and especially "light" RPGs that had attached RPG elements to some other style) were crufty and cumbersome and frankly kind of daft a lot of the time. And much of that was rooted in the, let's say "baroque" systems and subsystems that RPGs had inherited from the TTRPG space...which
mostly meant D&D. So they (again correctly!) concluded that it was good to simplify things to avoid unnecessary cognitive load, needlessly clunky mechanics, and unproductive "rough" patches of the overall experience. Unfortunately, that correct lesson was
rapidly replaced with a highly incorrect one: remove ALL roughness, never allow anything whatsoever that could potentially create a quit moment, avoid complexity at all costs, etc. Or, in simpler terms, never ever ask the player to
learn to play. This bad lesson was not quite noticed by the gaming public overall for a while, in part because this was an age of heavy casual player focus (e.g. the Wii was a HUGE turn toward the casual market, and the DS even moreso.) But by the late teens, yeah, folks had noticed.
The point of all this is to say that roughness in a gaming experience isn't bad in and of itself, but it needs to justify its inclusion. It should not be left to just sit there. It needs to contribute something. If it is
merely roughness for its own sake, it should probably be removed. But roughness that contributes to a feeling of mastery, that makes the player feel ownership over the experience, is generally a good thing, and shouldn't be removed without good reason.
Giant powerful boss monsters just sort of wandering around in newbie zones all the time? Not a great design. Not much to
learn from that, other than "the world is dangerous", which can be done in other, better ways. FFXIV and GW2 show two different ways to implement this that make it much more interesting. FFXIV has Hunt monsters: powerful enemies that only spawn occasionally in various grades. B-grade Hunts are always present (respawning in a few seconds at one of their random spawn points if killed), but they're "passive" and won't attack newbie players. A- and S-rank hunt targets are "hostile" and WILL kill you if you approach, but they're rare spawns, and generally players group up to tackle them collectively. Conversely, in GW2, the equivalent world boss encounters run like clockwork in specific places...but even low-level characters can participate, if they can physically reach the event location. They'll likely get downed, but since players are rewarded for helping downed PCs get back up, there's an incentive to help even low-level players (both the downed person and the helper get a small DPS buff; it's not much, but it means helpers do more damage for long enough that a 5s pause is in fact worthwhile.) Since these world boss encounters are on a regular schedule, many players will cycle through them, so it's rare for a solo newbie player to get caught unawares by such a thing.
Both of these are great examples of how game design is a technology that we can improve. The idea of having powerful creatures just randomly wandering the world isn't inherently bad, but it can have bad consequences that drive players away from the game. Folks have iterated on that idea to come up with ways that preserve the value of the core premise (the world is full of dangers, don't just blindly attack things, some monsters are too powerful for one person to kill, some things are aggressive and dangerous and you shouldn't approach them) while avoiding the problem parts that can seriously harm a player's experience. Likewise, From Software and their imitators have developed "hard but fair" games into an art form of their own; the games won't coddle you in the slightest, but their mechanics are consistent, telegraphs
are always there even if you missed them, and everything is predictable, you just have to
learn it and will get punished (often harshly) for nearly every mistake. That generally isn't my cuppa, but I know it has a dedicated following....and I also know that it includes variations in playstyles, with some openly looked down upon by the fan community as "easy mode" or the like. I don't know which ones specifically because I don't play From Software games (that kind of brutal difficulty
is not for me), but I do know that From Software specifically creates games they WANT the players to consistently finish, and thus they include options which are easier to execute, requiring less technical skill, amongst other things.