I think the trick to dynamic content is not letting people know exactly how or why things happen. Sometimes you should know like if triggered by a quest, but generally you shouldn't. Same with some rare spawns.
Regarding travel, I hope they are a little more judicious about run speeds and those lines of buffs in Pantheon. I never liked the idea of being able to easily outrun the environment in EQ, let alone bards going mach 5.
I think people tend to over-exaggerate travel problems from older mmos. At least in FFXI, it was a pretty trivial task for a prepared player to get to almost anywhere but the most extreme reaches of dungeons within 15~20 minutes. I just don't think it's worth abandoning such systems the way modern games have in a race to the bottom for player convenience.
In regards to Dorotea's concerns, I'd like to voice positives that might assuage you fears:
Personally, I'm a huge fan of the idea of groups of players clustering around safe areas such as hamlets further out from the main cities. If small towns have an inn (i.e. a safe bind point and perhaps other party-finding related things, such as a "noticeboard", perhaps food buffs) and a stable (source of rented mount that can travel along roads and paths to get you near your destination) then people naturally will gather there. Lacking the amenities of larger cities, like whatever the trade-friendly area would be as well as meaningful crafting stations, people would only be there temporarily. However since they are servicable as a grind spot for a given level range they would become necessarily a good place to stick around to reduce travel times.
I believe things like that, simple ideas that fit in a game and aren't overly complex are better solutions.
I'm sure things will be far better than the worst case scenarios I tend to focus on when discussing travel. Rapid transport from one town or hub to another (but only if you have already been there and "tagged" the stables/teleport) by itself would obviate almost all problems I raise. Not all of us favor such rapid transport but I see it as a big plus.
Level may not be a source of safety - not if some of the ideas above are adopted in terms of scripted encounters. Those will probably be tied to your level at the time of the encounter. Note that I do not at all think this is a bad idea as long as there is a rapid trasport system for when you are really in a hurry. My concerns about interesting travel were purely in the context of wanting some ...less interesting... alternatives available for when time is a factor.
People say rapid travel won't have an impact on the game, but I believe it will. I would reiterate that we already have pleanty of MMOs out there with rapid travel. Why does every MMO have to be convienient so that certain people who don't have time can play them? It seems obnoxious to push such features on every game so that it is available for everyone to play. The biggest reason to not have fast ravel is because it is a large part of certain classes like the Ranger, Druid, and Wizard (possible Shaman). Being able to buff mounts run speed won't remove the hurt fast travel inflicts upon those classes. Being able to just instantly click or take a train to a location after you have visited it also hurts those classes.
The closest I'm hoping to come to the taxis we have become accustomed to are carriages of some sort that basically function like land boats. You might get lucky and have it pull up right when you are heading out, or you might get stuck waiting fifteen minutes...and if you aren't paying attention when they arrive at the destination, or are AFK too long, they'll take you right back to where you started.
FFXI had airships on a schedule like that between main cities. Pantheon is from a different mythos and as a result air travel is probably not something that exists in that world, but a taxi system is workable. I'd prefer if it went something like:
System seems simple and straightforward without having egregiously far away bind points. If somebody refuses to bind at local inn then it's entirely their fault and the game devs shouldn't coddle them.