I was surprised and disappointed to see that the inability to use SELECT... INTO was a disadvantage.

Anything which takes that option away from developers is a good thing IMHO!

I have a rule for Table Variables which I am pretty strict about. If the developer can't tell me exactly how many records (to within 10) and that number is less than 1000 (reasonably small) records, the it should be a temp table.

You also missed one big advantage of a temp table. You can index it. You need to do this a bit carefully, because index names are unique, so if more than one process is going to run generating this temp table, then you need to add a "uniqueifier" to the index name (such as @@SPID).