In a studio environment, a smaller amp would usually be easier to tame and to mic properly, compared to a loud stack.
High wattage has little to do with how fat or huge your guitar sounds on the recording.
No doubt, most guitarists’ dream is to own a 100w tube head and a matching 4×12” speaker cabinet but in truth, they’re quite a hassle.
A 100w or even a 50w Hiwatt or similar, would be all too much for a 300 seats club, not to mention having to carry the whole thing to and from the gig.
By the early 90s, the low wattage tube amps were almost forgotten in favour for the transistor.
But trends tend to get their rennaissance and once again, guitarists demands the timeless sound of the tube amp.