Let's just take an example of the natural spell feat in druid wild shape morphs.
So you're a bear, casting heal spells and stone skin, this is perfectly acceptable and allowed. Now let's introduce a cross class build and pick say cleric, you are now able to cast similar spells while shifted and accessing the 'divine' rather than the 'natural' spell tree. Now let's multi class into a wizard, giving you further access to Arcane tree spells and abilities.
(Another point but I won't get into too much due to the delicate nature of it, warlocks as they stand can cast spells while morphed without needing *any* exploits or quick casting, the game designers probably just didn't realize it could be cast and forgot/decided not to bother fixing the combination)
So, now we are effectively a divine, fireball casting high powered grizzle bear of druidic rage. There is comments on animals having low intelligence and thus shouldn't be able to cast spells while morphed, however as an elemental form or even dragon form you are considered a higher intelligence creature and can comprehend complex things, making sense of cross spell books as dragons and elemental forms are beings of magic entirely.
Now, taking into consideration druid 'wild shape' morphs and combining poly-morphing spells such as "Polymorph self". It should make little or no difference for a druid to cast a spell or use his ability to morph, as to him they are considered the same thing, wild shape is defined as a magical ability in DnD rules, as is the magical effects of poly morph. Some people have said this follows suit and reason since you can morph into aberrations such as a tree-ant or even a spider and still be able to cast spells.
Are we being too literal in the feat "natural spell" allowing multiple cross spell books to be cast, as it is in no way constricted by in game mechanics or prevented?
I'm just after opinions on the matter
not starting an angry mob 