See, and similar spectrum - this is not a dubious assumption.
Sight has evolved several independent times on Earth because it's too useful not to. Plenty of species on earth have different sensory ranges than humans but they're all in the same basic region - not just for evolutionary reasons but for physics ones. If there is life on other planets the biology and evolution will be different but physics should be the same.
Frequencies of the electromagnetic spectrum that are significantly higher (mid UV and above) are energetic enough to affect a much larger proportion of molecules a lot more rapidly than visible light (ie cause damage). Too much of them and it's not likely there will be anything around to have eyes at all. Too little and it's not worth evolving the ability to sense that portion of the spectrum.
Frequencies that are significantly lower (mid infrared and below) are sufficiently un-energetic that they are hard to sense, let alone image accurately.
We also know that there are a lot of stars out there putting out light in the visible spectrum. Plenty in the non-visible spectra too, but the above reasons make that less desirable.
However, I agree that wasted light is likely to be a brief phase for technology reasons.