Magical Research seems written in mind for Mages / Wizards. However, Clerics and other Divine casters can also do research obviously. The problems I see are:
Intelligence bonus to research heavily favors Mages over Clerics. My players have brought this to my attention and argue Clerics should be granted a Wisdom bonus. I countered that Divine Power kind of helps the Clerics to offset this penalty.
Mages can use assistants, but this isn’t really defined well for Clerics. I’m assuming Clerics can also use assistants based on a post made by Alex here at some point, but again, assistants are also based around Intelligence and specifically mentions arcane casters.
You have to ask yourself if INT is like STR or DEX or CHA (works the same for everyone) or like INT (affects class features). It’s worth noting that many of the things that drive mage features via INT like knowing extra spells in the repotoire are not duplicated in WIS for clerics. In fact, aside from being a prime requisite, Wisdom does (if I recall correctly) absolutely nothing for clerics that it doesn’t also do for every other class. As long as they have at least a 9 wisdom, they don’t need higher wisdom for higher level spells, nor is their repotoire isn’t expanded by having a higher wis.
For my part, I would generally support altering it to key off of wisdom for this reason, but I think it wouldn’t be inappropriate to hold fast to the rules as written. As you pointed out, Clerics can essentially wait longer to build up enough divine power to get a bonus in extra “materials”.
I am not really sure that Clerics need a boost in that regard. They are also less dependent on magical research in general and get a boost by divine power as mentioned.
Wisdom is some sort of an uninteresting stat in ACKS as long as players don’t face many mages. Which seems to be usually the case considering how seldom anyone with spells comes up in the random encounter tables.
problem is the scale. an extra 5-15% chance to take half damage from a fireball isn’t going to make a difference in a lot of cases compared to an extra 5-15% chance to deal 1d8 damage plus 1-3, or an extra 5-15% chance to not take damage from a monster dealing anywhere from 1d4 to 2d10 which, while the higher stuff is deadly, is nothing compared to 5d6. And that’s ignoring sleep, which has no save.
Wisdom is easily the least exciting stat, although it doesn’t bother me because that is usually reserved for charisma and i really like what charisma does for henchmen and reaction rolls.
If I were the sort of person with enough initiative to cook up my own monsters and put them into random encounter tables of my own design (which I have repeatedly discovered I am not), I would create more monsters with access to minor spells for which a failed save is not as likely to result in a complete party wipe so that the high wis folks get a chance to experience a benefit more often.
I think the Intended bonus and assistance that Mages get makes up for their lackluster Domain benefits. Clerics get divine power, half cost buildings, and a hoard of zealots. I think that’s enough. Wizards should be best at researching spells, and the assistants rule makes apprentices valuable.
Tywyll has already explained the reasoning better than I could. If you want to buff up Clerics by making assistants more useful to them, you certainly can do so, but they are already a very powerful class.