It depends a lot on the baler. The 14T above is already kind of a compact baler. I spent many years putting up 5K to 7K bales a year on a John Deere 336 and it would move the Oliver 770 7000lb (both rear tires liquid filled) around quite a bit. Especially when getting into heavy hay, not to mention it would kick the governor in pretty well. We used a 15 foot draper head to windrow and on bad years we would windrow two rows together so we would be feeding in quite a bit of hay at a time.
Currently I have a JD 2320 which has a 23 hp motor and I know for a fact I wouldn't be able to run that 336.
What each person has to do is evaluate their money, situation and reasoning and come up with the answer to if it is worth it or not. There is no right answer.