There's no doubt that UR points are much more valuable than Arrival points. But the flexibility of Arrival points is what makes it attractive to people. Personally I like using a combo of both. IE- what we just did on a trip to Banff Canada. Pay 25k round trip for 1 using United miles transferred from UR, and pay the ~$75 taxes using the Barclaycard Arrival points.

At the moment I use CSP for Travel and Dining and Arrival or SPG Amex on everything else, besides Office Supply/Gas (Ink), and Entertainment (TYP).

A really easy way to understand why UR points are more valuable... A round trip flight from let's say, JFK to LAX would cost 25k United Miles, but would cost way more than $250, which is what you would get if you used Barclay points.