Why not? Well, bigger spring migrant wave and possibly baiting siege sooner, in addition to the clutter and potentially bins in a fortress that previously had none. I also believe performance troupes or visitors in general are possibly attracted by traded or offered wealth, though I'm not certain ( Just two embarks in same place with same fortress-designating macro in same time with one having trading offset by a year. ) .
There's couple other options for buying out first, or subsequent caravan.
- Spiked balls or serrated discs. Even wood's lowest modvalue will let your carpenter buy out the caravan in, like, something like month and half, and value multipliers go up to 30 with steel - if you're lucky and your civ requests trap components, you can buy out an entire smaller caravan with single masterwork ball of steel - though it may be not as attractive in cost as glass ones. As a bonus, one can like the exp more on carpenter, weaponsmith or glassmaker.
(Though note that wooden minecarts filled with water beat wooden spiked balls, provided you have source of water next to depot.)
- (Fire) clay crafts, ash glazed. With first spring magma kiln, it's free of materials, and for 5 jobs (of which three glazing jobs require no hauling and are very quick, making this probably better than producing clay statues for 2 jobs) and 3% (bug atm) of an ash bar you get a maximum of (glances at masterful masterfully-glazed stoneware ring) 1080*3 =3240. (Though minimum haul for no-quality ash + stoneware set would be 270, 240 for earthenware.)
- For subsequent caravans, high-value leather robe export, done using imported high-value leather (Which will cost less than 3% of value.) You can plant the leatherworker's workshop right next to or under depot (potentially minimizing hauling distance to workshop and to trade both to single tile with single obsidian casting). If you're going to want a clothing industry and military cloaks anyway, could also order a masterwork elephant leather robe (1980⛭), the likes of which on repeat is high and light enough to handle a caravan in a month.
- Some players like to trade away copies of books, though I don't think this is very impressive with the number of jobs it goes into making one versus their value. Still, something to consider as it is something you may want to produce anyway to prevent thieving visitors stealing the originals.
- As extension of above two, visitors arrive with lot of clothes and may carry books or instruments. You can strip-search them and confiscate contraband with dump command, though I doubt this will produce enough goods to buy out a caravan on its own.
- For pure fortress value (if you like numbers), nothing can beat architecture bonus on top of artifact bonus. A single ⛭⛭Bridge⛭⛭ with single artifact adamantine mechanism can reach 50 mil (double masterworks are huge pain to get, though, so I've only done this once). Aesthetically, masons are probably most valuable, being able to mass-produce blocks and furniture of vast majority of colours, even if they're not quite so useful militarily or economically.
- It's so commonplace it is trite, but...Magma. Or more economically, water. Right presentation of either will make traders an offer they can't refuse.