Status ailments are worthless to try and cast on the bad guys but they can sure ruin your lives when they cast them on you! I have found this on almost every game I have ever played. Was even more assured of this last night while playing Lost Odyssey. The amount of time and mana it takes to cast on trash mobs is wasted for about any status ailment since you could have prob either killed them or nearly killed them with that turn by casting a dps spell on them. And of course when you do get to a boss fight and think "Wow maybe poison will actually do enough damage and be worth casting here?". WRONG since almost every boss in every RPG game ever made is pretty much immune to about any status ailment you can cast. Sure you can poison or sleep a trash npc but why bother since they will be dead so quickly? In fact many times when you finally think how useful it would be to silence that 1 trash mob in the back row who is chain casting AE's you find out after wasting a turn "Oh guess even trash mobs are immune to them.".
Why bother even letting us cast the stuff?