I think some people like the "normal folk with artifact" plan because it can have a built-in reason why the characters have to stick around and do things. The travel-mcguffin can require a period of downtime or be unreliable, broken, or stolen. Maybe it only works in certain places at certain times.

Either way, there is nothing wrong with having a cast of 'Walkers doing pretty much all the same things that the Crew of the Weatherlight did. It just seems like using a cast of 'Walkers leads to the characters having too many opportunities to just leave a situation or hoard too much story on their plate at any given time due to being able to be anywhere on any plane in minutes.

As an example: Gideon working two jobs saving Zendikar from eldrazi swarms while also playing beat-cop for the Boros back on Ravnica. There's also Jace who is really doing a crappy job as Ravnica's Guildpact, considering he's pretty much abandoned the plane for months now between Kaladesh, Amonkhet, and now Ixalan. If Ravnica isn't a smoking crater when we get back there, it'll only be because of some off-screen visiting from Jace every couple of days during the Kaladesh and Amonkhet stories.

Jace may actually be a bad example for this though, because, now that he's an amnesiac, we may get to see what would have been a similar story if a group in a Neo-Weatherlight had crash-landed on Ixalan and couldn't leave for months on end while their multiversal obligations piled up and exploded without them.

Isn't Jace the opposite of that? He has a reason to stay, but elects not to. I feel like the Planeswalking dilemma is solved by just writing good stories. If your characters don't have incentive to be somewhere, don't send them there. I do think the sort of "I can't leave" horror plot has a time and place as well, but that's not really the crux of it I think.

Yeah, the problem with that is they want their cake and to eat it too.
A HUGE amount of Jace's problem is every time he's about to put down roots, he harrumphs about dangers and secrets and pushes everyone away.
Over. And over. And over.

It's now made mildly worse because now he has travel buddies, but ZERO incentive to get to know anybody out of their circle.

The big issue is ties, and it's the exact same thing you said. If your characters don't have incentive to go somewhere, don't send them there. Add on, if they have no incentive to stay... don't act like they care where they are.

Wasn't Kaladesh only like, 2 or 3 weeks, and Amonkhet was mere days?

I think for the most part Ravnica can operate without the constant presence of the guildpact. Since Azors created magical limitations on the guilds, the Guildpact only really NEEDS to be there to cover loopholes.

We should really have a set that lasts years.

Let's face it, making Jace the Living Guildpact was a terrible idea for more than one reason. At least they should have used that to create some real internal conflict when Gideon came to drag him along to Zendikar. Instead, they shoehorned that conflict between heading off to save Zendikar and staying to take responsibility into Chandra's arc (if you can still call it that) in the most artificial way possible.