Whilst 60fps is all well and good framerate drops
will be REALLY noticeable, as will the framerate
rising above 60fps.
A feature that locks the framerate to a set rate
would stop this being a problem. Say, for example,
I have a game that drops to 45fps in places and
rises to 65fps in other places, locking the framerate
at 45fps would be ideal for a smooth gaming
experience.
"This you have to understand. There's only one way to hurt a man who's lost everything. Give him back something broken."
Thomas Covenant, Unbeliever