Are #tables and #procedures 'not best practice' or 'bad practice'? I am working on a project and part of it is an interface tool that executes SQL code stored in a xml file to import/export files.

In the file, temp procedures and temp tables are used quite heavily (list of imported/exported records, logs, support tables, stored procedures for easier reading etc).

It has been decided by powers above and out of reach (luckily for both them and for me ;) )
that creating temp tables and temp procedures called during execution is 'not so good, maybe even bad' and has to be removed.....

This got me thinking and I would like to know (as I can't ask THEM), did anyone come over some general knowledge stating that 'using temp tables and procedures is not so good and should be avoided'

I know this question is a bit more vague then usual and is a bit subjective, but I would be really thankful for any insight from other, more experienced, wiser heads. 

Details (obviously , i cannot be totally specific, so please bear with some obfuscation):


There is a tool that handsles importing exporting files (mostly
CSV) to the DB 
the tool handles the common parts ie logging or
moving file based on success/error 
there are more interfaces, depends on deployment configuration, lets assume ... on avarage 10-20 executions per day 
XML contains phases for imort - init, validate, import/export, deinit 
data size varies (so does speed), usually takes less then 10 min to run, some take 1 hour maybe 1,5 hours. CSV have some 100s some have 1000s  some have 10000s rows, less then 100 'columns in CSV'
I doubt that the example you provide is a valid use case for temporary procedures (I don't see any benefit here to using #temp procedures over permanent procedures), but for #temp tables, which have a much wider set of use cases, the only way to fight these arguments with policy-setters is to run the code - using a full load and during typical workload activity - without using the #temp tables. If you can demonstrate to them that even one of these processes works worse without the #temp table, then that should be a valid counter. If they still won't listen, then this is not a question for this site - maybe workplace.