I think that you are confusing ACARS messages (those transmitted from the aircraft via airband radio or satellite) with ECAM messages (those that are displayed to the pilots). The former are mainly for operational reasons, for example so that ground engineers get forewarning of a failing component. ECAM messages are flight safety critical messages requiring pilot action and they are organised by priority.

ECAM messages are recorded by the DFDR/CVR but are not normally transmitted via ACARS. Pilots were not normally aware of ACARS messages (see MH370).

Your point is a fair one though. In the case of AF447 the crew, against their training, made no attempt at all to work their way through the multiple ECAM messages with the appropriate checklist so they died. The final report on QF32 shows what a high workload this can be.

Since AF447 was lost for nearly two years the ACARS messages were all that the investigators had to go on until they found the wreckage and the DFDR and CVR. Incidentally, one problem with those ACARS messages was that they are only timestamped to the minute and may arrive out of order which makes the interpretation of them more difficult.