> First, this results in exception messages that are a concatenation of multiple levels of error escalation. These become difficult to read and have to be broken up again in reverse order

Personally I don't mind it... the whole "$outer: $inner" convention naturally lends to messages that still parse in my brain and actually include the details in a pretty natural way. Something like:

"Error starting up: Could not connect to database: Could not read database configuration: Could not open config file: Permission denied"

Tells me the config file for the database has broken permissions. Because the permission denied error caused a failure opening the config file, which caused a failure reading the database configure, which caused a failure connecting to the database, which caused an error starting up. It's deterministic in that for "$outer: $inner", $inner always caused $outer.

Maybe it's just experience though, in a sense that it takes a lot of time and familiarity for someone to actually prefer the above. Non-technical people probably hate such messages and I don't necessarily blame them.