I am a bit late, but I actually do have an interesting theory why you can respec.
There are a couple of ways such a drastic change could actually possible. One of those is the cleric "spell" Wonder.
Now, what else could be a wonder that players could pray for? For example resurrecting people that you don't have the body of.
Or summoning, possible long dead, heroes to aid in your quest as some sort of mercenaries!
We just need some sort of high priest who could ask their deity on our behalf and then the agreement of said deity. Maybe we could find one lying around in some dusty catacombs? :thinking:
In all seriousness, I doubt they are actually going to give as that explanation, but it would be a neat little explanation to aid in our suspension of disbelief.
Would also explain why you could not resurrect other dead people or use respec to change your appearance to go undercover or so: "It does not fit into my gods plans." Still a device, but one that actually has some backing in the original P&P Rules.
