Crafted i90s aren't cheap, and limited time translates into limited gil income. What Gil I make naturally comes from the dungeon and raiding I do and little else. (Cashing in Seals for materials and selling them auction on top of gil rewards, and even that's split between that and slowly getting upgrades for Relic so I don't have to stop what I'm doing just for the Bombard Cores.)
This PvP character would be entirely focused on PvP, which means what outside currency he obtains contributes directly back into the Gil resources shared between them. I get to have fun, and a bit of return on my time investment.
Two reasons, Characterization and Simplicity.
First Reason: I'm a roleplayer. It goes against "Lin's" Mentality to focus her efforts on conflict between the nations as she fought for unity between those nations. Also, Cartneau is a traumatic place for her, she would not willingly return unless there was true and immediate danger there. That's enough for me to feel 'awkward' walking in out of character with her.
Second Reason: I play on hybrid keyboard/gamepad. Easier just to have a character designed specifically for PVP than to constantly remap skills, as I have limited slots to designate skills to.