I'm not sure if it's bad for the game. You could do the same thing in GalCiv2 and the mapsizes were much smaller. I usually have scouts in the early game with engines sensors and range modules because they are cheaper. After mid game I have big Cargo ships loaded with sensors. I usually stick with tiny and cargo though. Although I might try a sensor battleship.
@Dumhed there really is no reason to pickup starbase sensors.
It's been this way since GC2. Also, Frogboy showed off his own sensorship in his presentation for IGN.
But in GC2 there was an artificial sensorrange hardcap of 15. Which you could nearly reach by simply building the Eyes of the Universe Galactic Achievement. So anything that already had bonuses to its sensorrange like bigger hulls (from medium onward), planets etc could reach that limit in conjunction with the other racial bonuses to sensorrange (tech: starscanner1 +1, technologists party +1). That basically defeated all purposes to build any sensorships at all. Rushbuying the Eyes was more cheaper than producing a fleet of sensorships, and it was more effective because it increased the sensor range of everything you owned, so no positional managment required.
In a huge to immense galaxy size such a sensorrange was well justified considering the up to +1500 habitable planet count, however in a tiny or small galaxy it was broken (everybody can see everything).
In a way it was a player compensation for the fact that the/all AI don't play with a Fog-of-War, know where all habitable planets are, all galactical resources, and all fleets. (although in the particular case of planets the AI is coded to send a scout beforeahead). If this is equally so in GC3 I can't say, and I'm not going to make the call on this, because it will be better to wait for a general consensus here in the forums.
Anyway, one thing that always bothered me was when the AI used his constructors to put sensory modules on starbases when these modules are rather weak and do nothing for him. Might have instead build another base or a frigate instead.