I think this article at MTG Goldfish presents an interesting take on the problem Planeswalkers represent for Magic.
Because I typically ignore the throughline of Magic's story. I know a bit about how stories work and I have really, really gotten bored with Planeswalkers as primary plot-drivers because those characters haven't, in my awareness anyway, undergone any changes.
Each plane used to have its own stars and own narrative. They still do but now that narrative is, somehow, tied into what the Planeswalker does, and it's been this way since Return to Ravnica. That's five years of these characters doing not a whole lot, while the planes they are on tend to undergo some significant changes!
However, I usually tackle the issue of Planeswalkers from a gameplay perspective,
so seeing a very specific angle on what Planeswalkers do to Magic from that gameplay view and why is cool.
I also think it's going to become a bigger problem as Magic moves forward, if cards like Desiccated Naga and Companion of the Trials are any indication.
I really, really do not like where those cards indicate Magic is going. Having a card only be good-a 3/2 for 3 isn't terrible so WotC is totally padding the stats there to make this medicine go down-but having a card that is only good if you have a Mythic rarity out there-Liliana of the Veil and Liliana, the Last Hope being sold for $80 and $30 each, respectively, the most recent Gideon, considered to be one of the best cards in standard right now, $17 and the new Gideon will likely go higher-suggests that they are tying to move players away from a sense of place and more into character.
Now, from what I understand, those two cards are tied into the Planeswalker deck boxes, making this a little more palatable but...I don't like it. Having cards be so parasitic is bad, having them be parasitic with mythic rarities is really distasteful to me. It helps increase the reliance on luck (will you or won't you get the Planeswalker you need) in a game that already has plenty of variance.
But that's a very big aside.
When I talk about Planeswalkers I usually talk about how players don't have enough tools to deal with them, so they're positioned to take over any game (or format) where they are pushed.
What I hadn't thought of is how Planeswalkers are pushed in order to be the face of the story, and how that push will exclude other deckbuilding options due to their power.
And people might say, 'so what? Good cards always push out bad cards.' and they would be right.
Except: WotC has said that printing Lightning Bolt in the Modern era was a mistake because it removes deckbuilding decisions. If you can, you run Lightning Bolt because it is better than any other red removal card in the format. It's one of the reasons they don't want to reprint Counterspell.
I think the article makes a very good argument for how Planeswalkers make for a worse Standard by decreasing the decision tree for deckbuilding-just throw a Planeswalker in there, that solves problems.
I've done it myself-most recently with Knives (as you will soon see). So I think this trend bears a lot of consideration and watchfulness.