They're more expensive, but they tend to last longer (at least for JBC & this new iFixit iron since they lower temperature when not in use), allow much nicer more precise temperature control, and often can have significantly more power output and/or thermal mass (depending on the particular tip). JBC tips in particular can be changed while still hot, one-handed, thanks to their iron holders having a tip puller & holder built-in.

The delta in price isn't that different. Legit Hakko tips for FX888/903/907 are ~$7-10 each. Legit Hakko tips for T12/T15 are only $12-20 apiece. Twice as much, sure, but how many tips do you really go through? We're talking probably sub-$30 over many years in cost delta, for some significant advantages.

Legit JBC tips are closer to $20-40, but those are just a different price tier and much more premium. You can also get knockoff/clone JBC tips for $10 pretty easily, and in my experience they work just fine.

Yes, it makes tips more expensive. However, for the about of improvement in performance, I think it is worth it. I use Hakko T15 tips and they are about $20 each. Cheaper Chinese compatible toys are available and probably are good enough, but I don't replace yours frequently enough to care to find out.