Tape is an indispensable element in any basic gear. Whether something is nearly falling off, coming loose, moving around too much or about to break, tape will allow you to keep it attached just long enough to continue your ride and/or even make a (semi-)permanent repair. A roll of proper tape in your tool roll can safe your day. No doubt it will come in handy, one day.
Are you going to work on electrical cables with tape? Then VDE-approved insulation tape is essential.
Locking agents require a little more planning than tape, if you don't want to end up thinking 'if only I had used it ...'.
The vibrations of a running engine can cause the loosening of bolts, nuts and screws. This can lead to dangerous situations on the road, if you haven't secured your hardware.