praveen,
you deserve a padma award for you efforts in snooping down on 'degree coffee' and finding the etymology.
i had guessed the 3rd possible reason while i had concocted 2 'theories' of my own.
theory 1 : tb's like their coffee piping hot ; so given the blazing summer in tamil nadu (generally), perhaps the coffee of the tb's was vying with the met dept on 'degree' of heat
theory 2 : it's common knowledge that cups of coffee keeps you awake in the night. given the linear relationship between keeping awake and the academic excellence of the tb's, more the coffee the tb's drank, the more success they had in their academic pursuits.
one of the reasons i deserve to be banished from tb community (my father would have more compelling reasons though) is that i hate coffee....except the ones served in coffee shops such as barista, cafe coffee day et all.
i find the home made coffee too strong which hits my nostrils even before i can take my first sip.
also i find coffee stains the teeth much more than tea and it also has a terrible after-smell, almost akin to eating raw onion or garlic. it was also a put-off for me.
even as i was having small helpings of coffee at home, the switchover to tea was complete when i met a colleague after college who drank, am not exaggerating, nearly 20 cups of coffee a day. he lived on coffee.
the magical power of coffee in curing an instant headache including the famous 'otrai thalaivali' aka migraine is to an absolute, wholesome and nothing but the truth. my experiments with coffee during migraine stand testimony to this.
next best i can think of is the 'railway coffee', the safest food in indian railways - where else would you get boiled water ? but the experience of drinking coffee in a plastic cup with the rocking of the train is amazing.
here's my humble ode to the coffee
Boiling water poured to the brim
Draining life of the powdered bean
A cuppa, it turns to, wetting your lip
Touching your soul, as does each sip