Secondly, the D&D Team has repeatedly stated they find artwork one of the key appeals and draws for 5E. It's something they know from internal survey data, and the technical quality of their art is superior to that of previous editions, and overall less reliant on specific artists and style (4E's reliance on Wayne Reynolds for example).
As someone with at least some fine art background (A-level and pre-dip, but no degree), I very strongly disagree that the technical quality is superior to that of previous editions. I think that's actually demonstrably false, especially if we spin back to 2E. I think you could maybe make a case 5E has, at this point (not earlier in the edition) superior art, in technical terms, to 4E, but not to any other edition. And it would be narrow and somewhat subjective. Whereas claiming it re: 2E say would be simply laughable - 2E shows a vast array of highly-skilled art of varied styles (which was a lot cheaper to get before video games and movies ate most of the skilled artists). Far more technical skill and technical challenges overcome in that era than in 5E.
As for relying on an artist, I don't think that's at all an intrinsically good thing, avoiding that. You've suggested no rationale as to why it would be.
I understand you're not a fan of that strategy, or of 5E's art style, but it doesn't mean the D&D Team doesn't care about art. They probably underpay, but that's a different conversation, and D&D certainly leverages their brand to get high-quality pieces for below the rate they would probably deserve.
WotC's "management" (a vague term if there ever was one) probably doesn't care about art, but they're also not responsible for it? I've listened to many an interview from the D&D art team, including Kate Irwin and Emi Tanji, and they care and are responsible for art. Even the non-artist team like Perkins have spoken on how important art direction is, and name artists like DiTerlizzi for driving the look and feel of settings.
Sorry to quote ASoIaF/GoT at you but "Words are wind, Jon Snow".
Obviously we don't the exact cause of the issues with 5E's art, but what we can say is:
5E has no consistent art direction which could not be summed as "contemporary generic Western fantasy", and that, as someone else pointed out previously, which I initially disagreed with, but they were right about, it's extremely safe - even violence isn't really depicted as actually happening, merely incipient. There's even curiously little horror - a lot of the art in VRGtR is attractive, and in some cases borders on the disturbing, but grotesque? Not so much.
So what we have here is an art style that is ultra-generic, nearly indistinguishable from that of competitors and contemporaries, seems to actively eschew arts with unusual or distinctive styles (except where re-using art from MtG), and lacks any of the verve of even 3E's art. I didn't like 3E's art - nor 4E's - Wayne Reynold's is not an artist whose work I admire (respect, sure). But they at least had semi-distinctive styles, though 4E was undermined by Paizo largely poaching Wayne Reynolds to the point where his work instantly evokes PF, not 4E.
Anyway, the point is, I'm sure they care, but whoever is making the artistic decisions, the end result is extremely mediocre and middle-of-the-road, and this stands in extremely stark contrast to the continuing boldness of MtG's art.
Also, let's be clear - you are certainly incorrect when you say "management probably doesn't care about art".
Absolutely they do. Even at law firms and the like they do, where visual branding is very much secondary to client perceptions of value and the like. You think that D&D's art direction isn't being run past Ray Winninger? It is. Each individual piece? No, obviously not, but the general strategy and style? It definitely is. If you think Irwin and Tanji are off doing whatever they feel is right artistically with a hundreds-of-millions-dollars IP? You're dreaming, mate. That's pure fantasy. And Winninger is running the general strategy past people like Cocks.
I strongly suspect the real issue here is that MtG has "bold and varied" locked down as an art style, and thus some people high up in WotC have determined D&D must have "generic" instead of also having "bold and varied". Now that D&D makes more money than MtG, I'm hoping that might change, the balance of power might shift, and we could see something wilder from D&D. I'm sure Irwin and Tanji would prefer that, frankly. I doubt any art director truly wants to pursue the generic as hard as 5E has.
Finally:
Lastly, if 5E does get around Planescape, it's highly unlikely they won't commission DiTerlizzi for at least one piece (he's the prime candidate for a variant cover). The MTG example shows that the WotC art team actually is very aware of his history and is happy to leverage his personal brand. That said, there is no way he will be the sole artist, because DiTerlizzi himself has said that working on Planescape was a constant slog (and he was way underpaid then) and that he'll never take a job like that again. So even if he was offered to do all the art for 5E Planescape (and he wouldn't be), he wouldn't take that job.
None of which I've suggested, have I? It's like you've just assumed a ton of crazy stuff I said the opposite of.
In fact I even suggested just an equally dramatic artist might set the tone for 5E's Planescape. And why would anyone think of someone doing "all the art"? DiTerlizzi did not do "all the art" for Planescape, mate, what the heck? But he set the tone. And that's what Planescape needs - someone dramatic to set the tone, not the soft, generic, ultra-safe art of 5E.
And if they just get him to do the cover, and the internals are the usual generic mediocrity? Well, that'd suck. If they got him to do the cover and then the internals were not by him but with a strong and distinctive artist setting the tone (even a distinct tone from his), rather than going with the generic, great.
EDIT - I will say at least
some of the SJ art does seem to be a step up in technical quality from stuff we've seen even as recently as Strixhaven (which is not necessarily about inherent artist skill, note, at least in some cases it's simply about paying an artist more to spend considerably more time on a piece), so I'm hope that represents a general shift in the right direction. It's excessively generic but that could change too (also Spelljammer was always a bit generic-looking!).
