I doubt there will be low supply. Do you know how many Chakrams Pil has crapped out for people, or Sceamol Bands that Akvan has crapped out? The person in this thread who said he is 0/250 on ANY ra/ex is probably the unluckiest special snowflake I've heard of. I have lost count of how many junk ra/ex drops my LS mates and I have gotten in VW, and I don't think I've spammed any particular NM more than 80-100 times. I don't think these tickets will be as rare as people think, but of course time will tell.
As for your other concern that once you introduce gil into the equation, it makes it less likely that LS mates will help each other out, that is a necessary consequence of keeping personal loot. Any system whereby people trade stuff to each other will have the danger of introducing gil into the equation. That can be laid at the players' feet, not SE's, and there will be groups whose members are happy to trade tickets quid pro quo to help each other out (e.g., a mage trades a ticket for Toci's for a ticket for Mekira's, etc). In any event, the pros you listed for a gil incentive seem to outweigh the cons.