my girlfriend and I were talking about this suggestion and how stupid it is and we listed off the uses for grand company seals that we could think of from lvl1-60. The list is as follows:
1) rank up in the grand company
2) get cheap lvling gear cause you dont want to craft it yourself or are broke
3) crafting mats
4) chocobo
5) barding
6) stat reset cause you done flubbed up
7) squadrons
8) fc points
9) rank up fc
10) anima stuff
11) gc themed housing items
12) an fc room (goes along with the gc rank)
13) fc to gc affinity

im sure there is more that we didn't think of, but you get the idea. and this is just for trading in gear for seals.