Stratfor writes:

In our view, Nixon was as guilty as sin of more things than were ever proven. Nevertheless, there is another side to this story. The FBI was carrying out espionage against the president of the United States, not for any later prosecution of Nixon for a specific crime (the spying had to have been going on well before the break-in), but to increase the FBI’s control over Nixon.

programmer opines:

If control was the goal, it didn’t seem to work out as planned.