I'm concerned that if someone didn't really like Temporum, they aren't going to bother playing again with the expansion. Also, the majority of the time that I've introduced people to Temporum, it has been with the expansion. Or at least, with the player cards from the expansion, not with the new zones usually. And even then, it's been very hit or miss.
I think I've said this before, but the biggest complaint I get is that it feels like there aren't meaningful choices. And the reason it feels like this is that the best choices are only slightly better than the worst ones. People are used to games where a good/experienced player will absolutely crush a bad/new player, not one where he will only just barely win.
Well, you could try using the new zones too! Some of the new zones push planning ahead in particular. And some of the new things have very visible payoffs.
I do not think that an expansion sucks in people who did not like the original. It has a chance to reach more people due to new people seeing the game when someone pulls it out to try the expansion. And it has a better chance of impressing those new people if the expansion makes it a better game for them. But if they already tried it and didn't like it, sure why would they try it again.
When I was playtesting the game, people liked that it was close. I don't have any market research to really know what the world thinks. Obv. it would be trivial to double all bonuses and widen that gap.
As I've probably said in this thread even, I think the big mistake I made in the original is the choose-one zones. Some players park there and then think there was nothing to do, since they didn't do anything. And they didn't change history so they think changing history doesn't matter either. No-one thinks these things when playing with me, because they expect to lose and then lose; clearly there was something about what I was doing that was better. But the box never includes an experienced player.