Spelljammer is just more accessible than Planescape. You can just go from some standard D&D play to jumping on this cool magical ship and shooting off into 'space' and doing whatever, and then maybe you just come back. I mean, yes, you could just use Planescape as more or less a kind of super detailed MotP, but it introduced a LOT of fairly significant cosmology and whatnot, whereas Spelljammer is just kind of out there in its own realm and its easy enough to pick and choose what you use. So I think SJ is the more accessible of the two, overall.
part of the problem though was that as time went on the overall product quality deteriorated, particularly in the last 4-5 years. A lot of what was put out after 1993 or so was just crap. It wasn't well edited, playtesting was non-existent, and they clearly weren't doing good market research. So the worse their fortunes got, the less likely it was they were going to put out something that would right the ship. I think they were just throwing stuff at the wall and hoping something would stick. However, even when/if they had a decent product, how could they even get it to market anymore? By 1996 it was going to be virtually impossible to get stuff printed and distributed in any quantity, so there was no real possibility of a recovery at that point, whatever they put out in the last couple of years was basically just a last dying gasp.
That bump in sales is after Wizards bought TSR's assets. I suspect it came from actually having the money and staff to actually fulfill the orders that were coming in rather than anything to do with Birthright's marketing per se.
I think your basically right in terms of most people didn't really need or 'get' PS or SJ, but DS is a different story. It clearly falls into the 'swords and sandals' kind of fiction category and is pretty easily identifiable with anyone who read Gor, Conan, Barsoom, etc. back in the day (or Fred Saberhagen stuff). D&D cites those sources quite clearly and thus I don't think DS was much of a departure at all. Beyond that it was pushed as being kind of a more hard-core setting where the PCs would be tough, but survival would be HARD by default. That appealed a lot to many D&D players, a sort of slightly reformulated meat grinder with more story and slightly more heroic themes. PS and SJ by contrast are just 'out there', they don't relate to ANY fiction I know of at all, really.
I didn't mind it so much for in character quotes, but for some damn fool reason they thought it was a good idea to use it rules text.
TSR finance side apparently never gave the creative side any sales feedback. They didn't care what they made, as long as the advances kept coming from Random House.
On the plus side, that's better than today.
Today, a person can't pay rent ... because they can't pay rent.
I'm sure there are younger people today who are looking at this, shaking their heads and saying, "Wait.... people used to be able to pay rent AND have a disposable income? When was this magical time????"
