For business travel, this is great. I'm spending $1k on transborder flights where I earn around 3,300 redeemable miles as a gold per trip. Now, I would earn 8,000.
For leisure travel, this is a huge devaluation.
From a strictly business sense, this makes sense. However, with UA's recent poor performance relative to peers, this move is going to anger a lot of people they can't afford to lose.
As others have said, once again UA copies DL. If only they could copy the good things about DL (e.g., wifi, service, meals, etc.).
In addition, this doesn't apply to *A carriers. Once you get your spend on UA, there's basically zero incentive to continue to fly UA when you have a choice of other *A carriers. I suffered through UA to get $10K PQDs and immediately switched my flying to AC since I was on UAX anyway.