Lycanthropy is described in the Monster Manual as a curse. Some members of our party contracted it from a pack of werewolves in a recent session, and we consulted the infobox in the Monster Manual to see what effects it has.
The infobox "Player Characters as Lycanthropes" on Monster Manual page 207 states:
A character who becomes a lycanthrope retains his or her statistics except as specified by lycanthrope type. The character gains the lycanthrope's speeds in nonhumanoid form, damage immunities, traits and actions that don't involve equipment. ...
... If the character embraces the curse, his or her alignment becomes the one defined by the lycanthrope. The DM is free to decide that a change in alignment places the character under DM control until the curse of lycanthropy is removed.
...
Werewolf. The character gains a Strength of 15 if his or her score isn't already higher, and a +1 bonus to AC while in wolf or hybrid form (from natural armor). ...
To me, this sounds like a very positive curse to have. A player who chooses to resist the curse gains a passive buff to Strength (unless their Strength is already 15 or more) and some very potent damage immunities. The alignment change and the associated loss of PC control is conditional on the PC embracing the curse, and as such it's not really an issue. One can even remain in humanoid form to avoid socially awkward situations using the Shapechanger ability.
So, is there any mechanical reason to not contract lycanthropy, or a reason get rid of it after contracting it? What makes it a curse?