Re: Experience
I'm not certain about that either, other than they didn't want clerics to have too much fun. Or perhaps that the origins of clerics in the game had them as heavily-armored mace-wielding priests (for which Dex would be a dump stat) or that druids were a bunch of smelly, hide-wearing hermits (so they heck with Cha). I think they'd be great additions to their spell lists, because I don't see any major potential problems. A cleric of a god of trickery or athletics would likely use cat's grace, and a druid who wanted to really commune with nature or be a good animal handler (via the Handle Animal skill) would like eagle's splendor.
I'm guessing the reason is mostly historical and perhaps because they wanted to limit spell lists.
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On a vaguely related note, I once had some fun playing around with the concept of holy water for different religions in D&D. My group was playing a Forgotten Realms game in 3.5, which has a very extensive pantheon. As we were dealing with the four major elemental deities in that campaign, I thought to myself that the god of elemental fire probably is not lending his holy power to blessing water, his opposing element. Hence the "holy water" of the Church of Kossuth was actually blessed alchemist's fire. The holy water of a goddess of air was perfumed, blessed air. The god of earth had a special kind of blessed dust. Many other gods might use water, because it's fairly ubiquitous and cleansing, but it was fun to work out some others!