It is difficult to advise properly without being able to see what your situation is. If you could post some pictures it would be handy...

My guess would be that if the tiles were fitted properly the first time then there should be no issue with water ingress/damage? Are the other houses around you a similar design/layout to yours, so you can see what they have done?
If you are going to be stripping off the tiles anyway then now may be a good time to add some insulation.
Really need more info/details...

Bricks don't usually rot, they can blow when subject to cold but I doubt that would happen behind tiles.

The bricks could have always been this way, as they were hidden from view perhaps the original builders just used up all the damaged bricks for this section.

Plastic cladding is the last resort, I would reinstate the tiles if it isn't a massive job.