Outside of performance reasons or maybe somewhat lazy design actual technical zones are not really necessary. A good world design can use a seamless landscape and still create unique areas or "zones", landmarks, bottlenecks and impassable barriers. This should work better with the "if you can see it, you can go there" mentality than zones do anyway.
If we looked at this in a RL format, we have zones in RL, all areas of the USA are zoned, that being said you can still travel across a zone rather than following the roads, but lets also consider how difficult that can be if the area is heavily forested. If traveling off the beaten path across an area to skip the roads was made to be as difficult as doing it in RL would be, then maybe it wouldn't be so bad to have an open world.
But I have never seen a game that made travelling difficult yet, except EQ. And the only reason travel in EQ was dangerous is because there were tons of mobs all over the place, half who saw through invs, and you had to weave through them.
One way to do this would be to give some large movement speed bonus on roads, to try to keep players on them when travelling, a bit like Don't Starve does but idk that would probably feel odd in an MMORPG, I'm not sure.
Manouk said:I liked zones because it allowed me to compartmentalize memory of the place. However I prefered the seamless aspect, provided there were landmarks I could orient on, even in the distance, to get my bearings.
That's a great way of putting it and spot on. I feel the same way.