DISCLAIMER: This is mostly about BG pvp, in arena you have more coordination and better control over the situation. Your fears may get through because your team has other cc they can force trinkets and defensive fear breakers on. With BG pvp becoming a rated venue this becomes a legitimate concern.
Lets face it. Fear is a broken mechanic. It has been since vanilla. It is a spammable CC that renders the target useless, increases distance and doesn't always break on damage.
That mechanic on its own is insanely overpowered because if one is able to spam endless CC they will win in almost any situation: Arena or battlegrounds it doesn't matter.
Blizzard's solution has been to give nearly EVERY class ways to get out of fear in addition to will of the forsaken and the pvp trinket. Undead are usually the race of choice for pvp as they can break this form of cc that 3 classes posses that renders them helpless and vulnerable.
The problem is that so many classes, (melee expecially) have ways to break fear, that the ability is semi useless. Lets face it, i'm talking mostly about warlocks here although warriors and priests suffer some of the same problems (worse as theirs has a cooldown).
Warlock fear is used for a few different things.
Interrupting casts: Long casts only
Offensive CC
Defensive CC
Looking at the melee classes which tends to be clothies most vital threat its easy to see why fear has become a bad mechanic.
Warriors: Can break fears for 10 secs every 30 secs. Not including pvp trinket and will of the forsaken.
Rogues: Cloak can break fears and make them fairly unstoppable for 5 secs on a min 30 sec cooldown. Will of the forsaken and pvp trinket
DKs: Lichbourne and anti magic shell plus will of the forsaken and pvp trinket
Enhancement shammies: Tremor totem, spammable fear breaker. Pvp trinket
Paladins: Holy cow the only class without a fear break by default, pvp trinket although they could bubble a fear i guess.
Feral druids: Berserk aka 15 secs (21 with glyph) of fearlessness. 3 min cooldown. Pvp trinket.
Looking ahead untill cataclysm I see a few contradictions:
Blizzard states they increased the cast time of cc abilities because hasted casts were too hard to counter. The melee classes I listed have numerous ways to escape the fear after it has connected so is this really a necessary change? Especially considering that every class on that list will be able to interupt come cataclysm they all just gained 10 sec cooldown fear stoppers.
TL: DR
Fear needs a change. While the ability itself is a powerful one it is too easily countered and the counters completely outweigh the worth.