Actually in most Firelands AOE Situations Arcane is stronger in AOE. The problem with Fire AOE is that it only shines if
a) the adds have high or at least medium life
b) The situations do not happen more often than the Combustion Cooldown.
AOE situations in Firelands typically are low-health mobs which happen more often. Improved AE specced in Arcane is doing better Damage there (ABx4-AE-AE-AE-AB-AE-AE-AE-...), like for example the Ryolith Adds or the Second Phase adds at Ragnaros (not the sons, the other ones...).
So we have a weak Single-Target specc with gimmicky AOE feature.
---------- Post added 2011-08-09 at 10:21 AM ----------
Actually you aren't. A Shadow still does decent damage flying... true, less than a firemage, but not that
much less that it matters -> even at Alys a Firemage is no requirement (in our guild actually the Shadow
does the flying... as he did it the first raid id in firelands, they never wanted to "change a running system").
Only fight where I currently go fire is Shannox (nice crits ^^) as another person does the 30k stuff anyways there, or
if the warlock is not available (on holidays or ill or whatever).