I kind of wish I had specified in my OP that I was wondering why the magazines as a collection of articles was discontinued, nit specifically as a print medium.
I still think that even if a monthly pair of magazines is no longer tenable that some kind of periodic online release along the lines of what Dragon+ was trying to be would be nice, if only to provide DMs more resources and references to aspects of the D&D Multiverse.
The print 5E books love to drop references to Mordenkainen and Elminster and Tasha/Iggwilv, but aside from the DMG 2024 Lore Glossary there's very little to indicate to the many new players brought into 5E who these characters even are (for example, I just saw someone's post on Reddit concerning the DMG 2024 Lore Glossary that he appreciated it actually told him who Elminster was, saying that previously the only context he had was the wizard's cameo in BG3). Maybe a series of sporadic articles hosted online based on these characters could serve the dual purposes of introducing both new content to the game and new players and DMs to aspects of the D&D Multiverse.
For example, a new Demonomicon of Iggwilv series could serve the purpose of letting people get an idea of who Iggwilv even is in addition to providing lore on the Abyss and new options. Heck, maybe even get her alter-egos Tasha and Zybilna in on it; Zybilna could talk about the Feywild while Tasha might could be part of a rotating cast of spellcasters who introduce a new spell or magic item every couple of months or something.