I think the main issue, for me at least, is that while the Disney phone cast members will graciously accept several (my highest was 27) gift cards for hotel and dining plan purchases, but they cannot do the same with ticket purchases.
Apparently the ticket purchases are through a different system and they only allow two payment entries for the balance of the order. A single gift card counts as one payment entry.
Therefore, I'm left with the option of driving 50 miles south to a Disney Store to buy them in person, or waiting until I am in Orlando and use up my precious Disney time waiting in line for tickets.
However, this also brings up the point that FastPASS+ may or may not be available for a ticket purchased literally 5 minutes before I walk into the park...