Creating a new table from two existing ones

You can create a table that you want using DAX and the related function like you mentioned. It will perform better though if you create the table using the query editor or in the source database.  

If you have a sql connection to both of the tables the easiest way would be to select just the columns you want from each table and then inner join the two tables.  

If you don't have a sql connection then you can use the Query Editor's merge queries options.  They give examples of merging data in this article (you have to scroll down a bit more for the part on merging).  It is also pretty much the same thing as merging queries in Power Query for Excel.

Here is the basic flow you should follow to create a new table that contains columns from both tables:

1. Add another utilitymeters table (only do this if you want to keep the original utilitymeters table).
2. In the Query Editor select this new table and then Merge Queries
   1. Select utilityhistory as the table to merge
   2. Select meterid in both tables
   3. Set Join Kind as Left Outer
   4. 
3. Now expand the new columns and only keep the columns you want from the utilityhistory table
   1. 
4. Remove any extra columns you don't need from the utilitymeters table