This is exactly my problem and since I live in EU it's even worse.Here is my reasoning on why I like regional servers much better the international set up they have now.
First off I live in the US in the Pacific time zone, typically I play during the evening. These are just estimates based on data SE gave awhile ago for FFXI, FFXIV prob similar but about 50% of the players are JP, 40% are US and the remaining 10% are EU. Now then I can't really do much of anything with JPs I am not fluent in Japanese. I am actually Japanese American though but don't speak the language. For the most part I don't see too many EU players I could play with them however they aren't usually on when I play unless they play weird hours that lets them play in PST evening. So essentially I have a server where I can play with about 40% of the population and there are character caps on servers so no new characters can be made. Meaning I probably won't be able to play with 60% of the people on my server due to time zone differences or speaking JP.
Now here is the problem I am currently having with the game. I leveled all the jobs to 50 quite some time ago, pugged lots of mog got all the weapons then started doing Ifrit. When reilcs came out I wanted to do them. However the FFXIV community is pretty closed off when it comes to inviting new people to join their group or LS. Most people on the server have their set group of 8 people and almost never invite new people to join them. Basically I looked pretty hard and found nobody that wanted to do relics. I was stuck trying to pug hamlets but was very unlucky and didn't win any seals. More recently I try finding people on the forums on the servers forums, I might of got 700+ views on my topic but nobody was like hey join my group or LS we can use someone to go out and get relics together. Everyone seemed so set in their ways with set groups they made awhile ago that I pretty much had very little chance of finding 7 other people interested in doing this. FFXIV seemed to be much more clicky then any other MMO I played, FFXI, Aion, WoW, Swtor. In those games I had no problem finding a group to do end game.
The problem lies in only being able to play with about ~40% of the playerbase. When regional servers come out and I pick a NA server with about ~90% of the players will play at the same time I do, and speak English. I think it would be much easier to come by a group that wants to do some serious endgame. Which is why I can't wait for the regional servers because I actually want to do stuff in FFXIV not sit around in Uldah thinking maybe ill get lucky today and see a good shout so I can get some progress on my relic quest.