I've never made that observation. However, it wasn't just the microphones, but the whole recording chain was tube based. Tube recording consoles, tube compressors and EQs, tube tape recorders and tube vinyl cutting lathes. Sometime between the early 1960s and mid 1970, nearly every major studio switched to transistors with the one exception being the continued use of tube microphones.
In the studio environment reliability and consistency are paramount factors. Additionally physical size and heat management come into play. What worked on a 4 track recorder won't work when scaled up to 24 tracks. What worked on an 8 channel console won't work on a 48 channel machine. The microphone used in the morning session has to sound the same when used for an evening session. Engineers complained about this problem with tube microphones.
Interestingly enough, in this century tube components have made a big comeback in the studio environment. The reason is the abandonment of analog component and their replacement by digital recording tools. To balance the sound of digital recorders, engineers and musicians started re-using tube effects. So they might use a tube microphone going into a digital hard drive recorder. Or they might run the final mix down through a tube compressor or tape deck.
In the studio environment reliability and consistency are paramount factors. Additionally physical size and heat management come into play. What worked on a 4 track recorder won't work when scaled up to 24 tracks. What worked on an 8 channel console won't work on a 48 channel machine. The microphone used in the morning session has to sound the same when used for an evening session. Engineers complained about this problem with tube microphones.
Interestingly enough, in this century tube components have made a big comeback in the studio environment. The reason is the abandonment of analog component and their replacement by digital recording tools. To balance the sound of digital recorders, engineers and musicians started re-using tube effects. So they might use a tube microphone going into a digital hard drive recorder. Or they might run the final mix down through a tube compressor or tape deck.