But I love the idea of planejammer…..
So do I. I've never cared for the actual spacefaring aspect. I'd much rather spelljammers be
necessary for timely travel across the astral sea. I'm fine with going to the moons of the setting, but I'd much rather travel to other settings take place by traversal to the astral sea. Especially given the 4e cosmology where all the planes are just aspects of the astral sea or elemental chaos carved out by deities or powers.
I think planar travel is
absurdly boring in D&D, because you just use plane shift or gate and boom you're basically there, and those are your only options outside of "you find a portal". Super boring, gated behind spellcasters, just not interesting. I think spelljamming is
way more interesting. Now it's difficult to even
get to the afterlife. You've got to build or acquire a craft to just to get to the other planes, and travel is suddenly not instantaneous and solved directly from the spellcaster's character sheet. It's very thematic and unique to D&D, too. You could easily have an adventure like The Odyssey or Jason and the Argonauts in the astral sea, with small islands in the astral sea created by being living there. Or a pirate campaign inspired by One Piece or something. Or inspired by Elric. The trappings of Spelljammer always felt like they push you
away from doing that.
The thing I
don't like about Spelljammer is probably what most people do: the space opera aspect. Everyone I remember wanting to play it in the 90s wanted to play Star Wars in D&D or Star Trek in D&D or RIFTS in D&D. None of those appealed to me; I'd rather just play dedicated systems for those settings. The interstellar travel itself isn't interesting to me. The jargon built around Spelljammer was a big turn off to me, as well. I just don't find it interesting to invent brand new terms when seafaring ones basically already work. I also don't really care for Aristotelian physics. I wouldn't miss the aspect where spelljamming helms blocked spellcasting. I'd rather they have a key and work more like a ship's helm than something you wear. Frankly, I always associated the name with windjammers, not "jam" as in "block" or "jam" as in "shove spells into". I also never really cared for the creatures unique to Spelljammer, so if I use the material I'm not that interested in those. Why, yes, I have often said that I don't like Spelljammer, why do you ask?
I just don't think it's interesting to travel from Oerth to Krynn to Toril, etc. Most of the published settings that are actually fleshed out are little more than palette swaps, so it just never feels necessary to travel to another setting that's 95% identical.