Maybe if the game allowed some way to have two armours or shields and you could just swap them about to the cards you want. Shame there's no mechanic for this.
I can't be bothered to explain all the faults in your argument but
Perhaps the strongest argument against this idea is the fact that priests will be harder to kill should pneuma and safety wall are allowed to be stacked. Yes, they will be harder to kill but it's not impossible.
You want priests to be impossible to kill? Pneuma is a 3v3 OP skill that would also make champions broken if it could be stacked. It's a stupid idea.
Oh and:
Since when did Pneuma bypass Land Protector? Are you kidding me?
It doesn't, that's my point. Making pneuma/SW stack won't make a difference to LP so why mention it? Same with TCOF.
-1.