For what reasons, is isopropyl alcohol widely used as a cleaning solvent?
From this Wikipedia article 


  Isopropyl alcohol dissolves a wide range of non-polar compounds. It also evaporates quickly, leaves nearly zero oil traces, compared to ethanol, and is relatively non-toxic, compared to alternative solvents. Thus, it is used widely as a solvent and as a cleaning fluid, especially for dissolving oils.


 You should try Googling first :-) 

Also, the antiseptic properties of isopropyl alcohol are an added benefit (over the other lower alcohols).

As you pointed out, methanol is notoriously toxic, so using that as an industrial cleaning agent is a no-no.

Ethanol for industrial purposes is often available as denatured alcohol; which has added impurities to render it toxic and/or alter its taste and smell.
These impurities may interfere with the equipment (you mention the electronics and aeronautics fields) you clean it with.

However commonly available isopropanol isn't denatured (then again, there's no real need to denature it). Since it is lacking in added impurities, it presents itself as a better choice over ethanol for cleaning such equipment.