The funny thing there is, Dax sees a star system five lightyears away, one she calls the "nearest", and Quadros-1 data helps identify that system and get a positional fix. But in "Destiny", there's a star right next to the wormhole, giving a comet a pronounced and glowing tail!
alone give no real possibility of fixes, there being too many almost exactly alike - so Dax ignored the one right there and wanted the computer to analyze the nearest star system
, with a more unique ID thanks to the presence of planets?
The thing is, the UFP has access to powerful telescopes that can probably give fairly good spectrography on distant planets; today's systems are almost capable of that already, after all. Yet the UFP or Starfleet clearly lacks the means of getting realtime
data on distant systems - it cannot tell that the Doomsday Machine is eating planets or the Ceti Alpha system is being rearranged until a starship pays a close and personal visit.
Various explanations may be offered. Perhaps "realtime telescopes" (subspace sensors or whatnot) lack the required range, even in the case of massive installations such as the Argus Array, just like it seems that starship sensors only tend to get "passive", time-lagging data such as planetary classifications beyond a certain range, and have to fly close to the planet to get up-to-date information. Or perhaps subspace telescopes do have the range, but are extremely expensive to build and operate (Argus Array again), and thus have only been able to map a tiny fraction of the galaxy so far, focusing on one target at a time. With the number of interesting targets out there, it might be thousands or even millions of years before a telescope could afford to take a second look at Ceti Alpha, for example.
The exact nature of the limitations is debatable. But their existence seems obvious, and gives Starfleet the reason to keep sending both crewed and uncrewed exploration spacecraft. Some other unknown but pressing reason may make them favor crewed over uncrewed - or then the thousands of probe missions per each crewed sortie simply go unreported in the episodes and movies.