So I don't think there will really be any need for /sea. It was essential in FFXI because so much depended on your party formation, which was not really a great game element. I think this is at least one area where SE has learned their lesson. At least, I hope so.
/sea will be essential if there is any sort of increasing difficulty in guild leves, dungeon zones and so on. It might be fun to kill 10 rabbits with 3 rangers, ranging from very little skill levels to having played since the servers opened. You can't do that in any sort of advanced or difficult event where the mob(s) can actually kill you.
If its possible you can and will die without proper support, you need to not only know what role in the pt a person will be playing but also the abilities that person posseses within that role. Even if there is no lvl 1 and lv 75 there will still be people who are new to a class with no real abilities and an advanced player with everything available to them.
You either have to cut difficulty to have all content completely soloable by any job (so you can invite anyone and it doesnt matter) or you force all difficult events / leves / whatever to be done within your LS if you cannot guage the person's advancement within thier class with a search. Neither of these really seem desirable to me.
Of course /sea as it currently exists would be completely inadequate to guage a leveless system. There would need to be an advanced search of sorts.
Edit: Would like to add to this.. I don't want a grouping system that devolves into the equivalent of SAM, SAM, SAM, RDM, BRD, COR onry, but I do think there should be non 'hardcore' type end game leves that will require something on the nature of DD x whatever, a support or 2, perhaps a tank. Edited, Sep 3rd 2009 6:15am by Yashnaheen
Yash Nahain - Keeper of the Moon Miqo'te, DoM / Goldsmith
Ghostface Spidercarpet - Highland Hyur, Gladiator / Armorer
Don't know which one to keep yet.....