Naked bulbs deserve a separate commentary. In the 1920s, when part of the population was caught up in the propaganda about building a new socialist life, one element in the struggle against bourgeois values was an attempt to eliminate unnecessary decoration. The new aesthetic was minimalist, functional. In its extreme, this minimalism encompassed a rejection of "unnecessary" decorative details. Included in this category were lampshades and curtains, which were criticized in the press.
"Lenin's bulb" lit up the victorious proletariat all the brighter without lampshades. Still, the disadvantages soon became obvious: not only did the light of the new higher-watt bulbs cause glare, but in a public space, a bulb hanging with nothing to shield it could easily be unscrewed and carried off. For public spaces not under comradely surveillance (archways, courtyards, entryways) it was desirable to have "vandal-proof" equipment.
The protection against theft has made it hard to change bulbs and fix sockets. For example, in some kinds of elevators, bulbs can only be changed by a mechanic who has to go down the shaft onto the elevator roof. Elevators like that can remain without light for weeks.
The appearance of even higher-watt light bulbs in the 1930s coincided with that decade's promotion of a "cultured" way of life. Lampshades and fixtures were no longer criticized, as they, along with curtains and a tablecloth, were signs of domestic culture. But lampshades were mostly used in rooms in which people lived. To this day, entryways and staircases almost always have naked bulbs.
During perestroika, you couldn't always buy bulbs. At market stands there was a brisk trade in a new item: burned-out bulbs. The purchaser of a burned-out bulb had the opportunity to commit an act of robbery by means of substitution: he would unscrew the working bulb in his entryway, put there by the local housing authority, and take it home with him; in its place he would screw in the one he just bought, as though it had simply burned out on its own. To steal it outright would have been unethical, but this way it was more or less okay.
See photographs "Fixtures from a past time: socket and switch" and "Three bulbs in the lavatory" and also these photographs of naked bulbs in a hallway.