All my scopes have adjustable objectives..
And because your thinking of a scope in a magnification of 4.5-14 power and,in terms of long range shooting at 800yrds I highly suggest you get it..
Like Big Country said if you shoot long range its nice to have
because it focuses on the target and eliminates parallax..
But they are really not really required on quality scopes of 10 power or less and targets at400yrds and less.
Yes I say you are one that requires one and the question I'd be asking is weather you adjustable ring bell, or a side focus adjument turret..
Personally I'd go with the latter cause you don't have to take your eye of the target or move your head while focusing two very importantant things while adjusting for parralax...