Yes, Tidus is a little annoying at times, easily the most out of all main FF characters IMO.. but he's not that bad when he's either quiet or being serious
And about noone knowing his name in the game.. I think that's because you get to choose his name, don't you? I can't remember for sure if you do, because it was a long time ago I played it last time, but it would make sense - you can't make characters speak out a generic name in an acceptable way (at least not yet, maybe on the next generation consoles though?)