Of course. You can use them to offset the cost of in-flight purchases, luggage charges, lounge access, and flights paid in cash (by bouncing through GCs).

Whether these are valuable to you specifically is a different matter.

At the very least there's always the GC resale market. If you're uncomfortable with that, you could purchase GCs and donate them to the charity of your choice, taking the tax deduction. Or, if you have a family member that often uses (different airline), switch your annual credit to that airline and gift something cool to the family.