[Karinya]

I'm interested how a customer is to know this before purchasing ToAU?

Previews, game info websites, reviews, forum discussions, word of mouth (including in-game), maybe even watching over the shoulder of a RL friend who already has it.

If you don't want to buy it on release day based only on SE's marketing, then don't. In fact I didn't buy any expansions so far the first day they were released, or even the first month. Nobody is forcing you to buy TAU; not buying TAU will not even cause FFXI to stop working. There's still fifteen jobs you can play using only RoZ which all NA players got for free. Nobody is going to exclude you from parties because you can't sub PUP. (People who didn't get RoZ for free do have a legitimate beef with the overpoweredness of /NIN, imo, but since it's been included in base versions for several years, it's not much of an issue anymore because of simple demographics.)

Yes, you have a more restricted choice of quests, missions, other content (Assault, Besieged) and exp camps, but whether it is worth $30 for those things is a decision each player has to make on his/her own. It's really not that hard to get an exp party going somewhere besides the usual overcamped hellholes - most people are sick of them, but just don't know the alternatives.

I *do* have TAU now - and I don't regret it, although some of the exp/merit camps are tedious I really enjoy assault and besieged - but I didn't buy it automatically without thinking and I don't think I was pressured into buying it when I did.