Short of joining to a dimension table to get a member's description, is there a way to configure the blend table build process to use a member's description (alias) instead of the member name?

You could potentially point the datasource to get the descriptions instead of the labels, but then you need transformations rules for that too.
You can of course point your data source to get whatever into the Accounts, but bear in mind that if you are doing any type of aggregation on accounts that will not work with anything besides the true account labels.
you can easily build a view in SQL to be very generig to always return the descriptions instead