In terms of Clerics: My Cleric usually uses his fourth level slot for a higher level Spiritual Weapon, Banishment, and Death Ward. Clerics usually also get some nice 4th level spells from their domain.
Banishment? Divination? Deathward? Control Water*?! And you are complaining about 4th level cleric spells? Guardian of Faith might be a bit more specific… but it lasts 8 hours and you can't sneak past it.
*Empty a waterskin on the ground, making a puddle. Cast Control Water-Flood. Drown your enemies. Laugh.
Percentage-wise, I suspect that it is very low. Less than 5% and probably less than 3%. IIRC from reading the monster manual, elemental resistance and immunity tended to be the exception instead of the rule, even for fire. A lot lower percentage than in 4E or 3E.
Odd levels of spells tend to be cooler than even. There's some good utility at 4th level though. Plus 3rd level spells are pretty iconic, when magic typically "got good" so 4th just doesn't seem as awesome in comparison.