Temple worship is central to God's plan. There are ordinances that can only be performed in Temples dedicated to the Lord.
As for when it's going to occur and how it will occur when there is a building there already, that's up to God to figure out. By why would Christians not want to see it built? It's one of the signs that indicates that Christ will soon return.
Temple worship is designed to maintain the 'holier than thou' superiority it establishes for the cleric classes. It's a business model designed to limit competition among worship leaders and maintain established cash flow patterns in the worship industry.
Historically, it's a very successful plan for making a good living as a public speaker.
What was the job of the Levites, and who gave them that job?