I wonder why they can't do the same thing?
Just wondering how they would do the same thing gives the answer.
Stellaris, structurally, only supports a certain kind of victory conditions, based on expansion.
The sensor ship problematic was more of a GalCiv3 thing though where you just designed one ship, built it in turn 2 which ended the exploration part of the game.
In Stellaris, it is nothing better.
Sensors, at the moment, are one of the worthless features.
At start, the player surveys the planet within the zone of influence. It is mandatory to take advantage of the discovered resources.
Sensor technology is not that involved in the process of surveying.
Once it is done, the player will no longer survey systems. The player will scout systems, looking for appropriate planets. At this stage, a better sensor technology would be useful since any system taken in the sensor range is scouted.
The problem is that the sensor technology is barely available. It will take time to research it, move the ship back for upgrade and send it back to its latest scouting location. It is not worth the investment.
Later on, the player has less and less interest to scout as the closest planets to the empire and fitting an expansion scheme are enemies' planets.
At this stage, the player also suffers losses among scientists. One of the quickest way to level up a newly recruited scientist is to survey systems. The player shall survey every single system possible to reach that end.
So, in the early game, when the technology would be useful, it is not available.
In the mid and late games, when it is available, it no longer fits any purpose.
They probably failed at getting what they wanted:
- a zone of influence, where the player could build mines, research stations etc
-a zone of control (covered by the sensors) that the player could effectively forbids.
Fleets were supposed to be able to move freely around. Giving the option between flying in no man's space (the zone of influence minus the zone of control) or intruding onto the zone of control.
Sensors have no value in Stellaris.