That is one of the reasons I want to drop DEX.
DEX can be used for saves, attacks and initiative. It is really strong.
By making it WIS+CHA instead of WIS+DEX, we in effect make this ability worse for a combat character.
Now, DEX+CHA vs WIS+CHA is more interesting. But DEX+CHA makes the feature a tempting dip for CHA casters who also want to use DEX for weapons, which isn't rare (every bard). WIS+CHA is a pair of stats that nobody uses for an attack/defend pair. I mean, maybe you could build a hexblade ranger cleric triple dip that uses wis for casting?
And it does open up a strong Cleric|Hexblade.
DEX became strong because of things that were added to it:
1E: AC, missile attacks, initiative bonus to missile attacks only and surprise, some saves at DM discretion IIRC
2E: AC, missile attacks, initiative bonus for all, surprise, again... some saves IIRC
3E: AC, missile attacks, initiative bonus for all, surprise (?), finesse weapons, saves (did it modify Reflex?, I don't recall...)
5E: AC, missile attacks, initiative bonus for all, finesse weapons, DEX save
CHA is becoming the same way with all the classes so dependent on it and I don't like seeing yet
another feature based on it. You are basically tying non-physical ability scores to a physical thing like combat. Now, a character can have a great defense and dump DEX as well as STR?
Given Paladins already use CHA, I could more see them having a DEX + CHA combo for unarmored defense.
At any rate, with your logic Wizards should have a AC of 10 + DEX + INT to represent their use of logic, tactics, and quick thinking to make them hard to hit. Where does it end? I can argue just about any combination and just remove armor from the game.
Anyway, of course try out whatever variant you like. I like the concept, I am just sure about the execution.
I don't think they dropped it, certainly not as bad as the Ranger, but they sure as heck fumbled a bit. I think they didn't went far enough with the design to make an INTERESTING class instead of a functioning one.
They went too traditionalist by not looking further than Domains. Same thing I would say with Wizards and their Schools. (I think they should have conflated all the School Specialists into one subclass with options instead of 8 nearly identical ones, giving us room for more out of the box Wizard subclasses,but that's for a different thread).
Yeah, I completely agree with that.
So a Mage class with a Wizard subclass who has Schools.
A Priest class with a Cleric subclass who has Domains.
Now, interestingly, you can do this retroactively. That is one avenue for a "5.5", where they reword the existing base classes into subclasses. 4e did this with "essentials" in a sense. (note that they didn't do a great job in 4e with the essentials retroactive subclasses, but that doesn't mean this approach isn't possible to do well)
That permits existing 5e characters to continue to work exactly as before, but opens up a new design space.
Sure, subclassing Wizard (school-focused) and Cleric could work. But then again you could subclass Barbarian, Ranger, etc. into Fighter, and so on until you have just the basic four classes.
To me all that is needed is a bit of tweaking with some of domains. For many of us, IMO, the traditional "cleric" is the War Domain as the front-liner type from 1E. It would be nice if the other domains more strongly focused in other directions. I think you've hit that on the head, no doubt!