I will voice the unpopular opinion. It's not the cue.
With any change in equipment there will be a break-in period. Give yourself a few weeks to get used to your new cue. If your setup has changed due to a change in where you put your hands you might not be hitting the cueball in the exact spot you want to.
Nailed it. I moved up to a 60 inch cue a few years ago and noticed a huge improvement in my accuracy (my stroke was much straighter)...but lost some of the juice. I found it a few weeks later.
FTR, I think EVERYBODY would see advantages in using a longer cue, not just us tall guys. For tall guys, it allows us to use the same wingspan on the cue without having to hold the butt sleeve or use a two inch bridge. For everybody else, the game on a 9 footer or bigger just "feels" better with a little longer cue. The balance, stroke, everything just feels "more right". Can't explain it, but recommend you try it if you can...