That's great if I travel Amtrak a lot. Not if I also, for example, fly American Airlines or stay at Starwood hotels a lot and want to be able to redeem there.
Even before I had the Chase Sapphire Reserve (which gives 3x points on travel, but also has a hefty annual fee), I pretty much only used my AGR card for Amtrak purchases. With the program changes, it makes sense for me to purchase trips rather than redeem points more often. So, I'm earning more and burning less. I don't need more points.
And, if you don't spend a lot of money on non-Amtrak travel, it's not a very useful feature.
The AGR card has always been a poor value proposition. Even the link in the OP says that it's great for regular Amtrak travelers and that's about it. It's always made a bit more sense for folks who travel more widely to use another program and its card. SPG has always been a good choice, as was Chase's UR, when they had the AGR card.
To be honest, the blog post linked in the OP is just a fluff piece. It's not so much positive as it is factual. They don't even have links to the cards' applications -- but they do send you over to pages with referral links on the SPG cards.