Let's think this one through. First you said you have too much length. But the only reason given has nothing to do with length. Nothing about having to coil it up, no room for yards of cable, nothing like that. Your whole "reason" seems to be some vague fear of "something to do with capacitance." That is not a need. That is a feeling.
You asked if there is any reason not to. Sure. Plenty. Phono leads are real finicky. It is real easy to make one noisy, real hard to make one quiet. You might do everything perfect, beautiful solder joints, put it back together, monster hum. No idea why or where it came from. Back you come looking for advice from the same guys who failed to warn you in the first place. Not me. Other guys.
The best reason to not do it really is there is nothing to be gained. But plenty to be lost. Whatever your lead is worth now, guess how much less it will be worth when sold as "I cut it down because of something to do with capacitance but I know what I'm doing trust me."
Thanks. Pass. Future value: nada.