KarinsDad said:PCs can only cast one or two spells per round. Having a few extra spells is white noise when compared to picking out an optimal spell for the situation as compared to a suboptimal one.
Clerics (and divine spellcasters in general) are a special case as compared to Arcane Spellcasters.
One major issue is there are a lot of cleric spells that you really need occasionally but which are not all that helpful to have on a spontaneous list (Remove Blindness, Regeneration, Raise Dead). These spells eat up a limited number of spells known but it is a major issue if they are simply not known by the favored soul. Scrolls only go so far.
The second one is that classes like the warmage have a very broad and flexible list (at least in terms of having the right spell to actually cause damage). You don't see the same ability to adapt on the fly with a cleric spell list as it has a rather limited number of spells.
The last point is the lack of domain spells -- these are powerful spells, often drastically expand options (e.g. Teleport in the Travel Domain) and can be cast spontaneously with the right feat (Domain Spontaneity). Because domain spells are not on the general divine list, some of the best spells are not available to be selected by the Favored Soul.