I think being coherent (tonally, aesthetically, and in terms of world-building) and making a world that makes some sense is what's important, personally. All the most powerful and memorable worlds are, and they tend to lose something when they deviate from that (as they often eventually do, over time).Spinning off the Revel's End/Prisoner 13 thread because I don't want to thread jack that one.
D&D has always embraced what we would call "magitech" and science fantasy. The pulp authors that dominate Appendix N did not make the same kinds of genre distinctions that became more common in publishing later on. The line between magic and science and fantasy and future were much fuzzier (see: Vancian).
Long before Eberron, D&D depicted nations that codified magic into science analogs. Long before 3E's "sheens" robots and layers made appearances in D&D. "Lovecraftian cosmic horror" IS science fiction.
What are your favorite blurring of lines between sci-fi and fantasy in D&D? What kinds of science fantasy have you embraced in your games and campaigns? Where do you think D&D needs MORE science fantasy?
That can be heavy magitech (Eberron, World of Warcraft, etc.) or near-zero magitech (Tolkien, Birthright, etc.).
Obviously not everyone agrees about coherency - otherwise Mystara wouldn't exist