I got one of these tokens at RAUH and VA levels -- but unlike usually, I haven't been able to requisition a ship with them. What are they used for?

You get costume change tokens for you character's avatar. Like changing your costume to reflect your new rank pips. And ship customization when you acquire a new ship.

Like lordfuzun said, Costume Change Tokens are for your character, not your ship. Whenever you commission a ship you get 1 free Rename and 1 free ship customization (not including changes to bridge or layout). Anything else after that, and you have to pay EC to the Ship Tailor.

You are not getting a free ship at VA. You can buy it from C-store, with zen. Also, ship you received at level 40 is good for everything.
You can easily buy a ship from exchange. Mirror universe ships are cheap and easy to get.

I was just wondering what the tokens were used for. And the tailor and ship customization was so cheap I thought that couldn't possibly be it.

The tokens have been in game for a long time, way back before F2P costume changing could become quite expensive and the tokens were more useful back then.

If you do a major makeover to character facial and body dimensions mid-game the EC cost of the 'plastic surgery' can get rather high.

This is where the token comes in handy.

Ah. Thankfully I've customized my avatar to my liking to the smallest detail from the very beginning. XD

[Although I changed my hipsize the other day -- I didn't see any notable cost...]

Each change can cost up to 1,000 EC if I remember right. So if you changed everything it would be at least over 10,000 EC. Hence the token.

Kyle