For some pax this is true, but not for all. For me, the upgrades have become a better value with the new chart.

Before, I was paying ~USD2000 for a K fare to/from JFK. With 80,000 miles (if you were lucky and could confirm both ways, which in practice never happened), you could get a J seat with a cash value of ~USD8500 (if you go based on discounted J) or ~USD11500 (full J). If you take the difference between the cash value of the J ticket and the K fare, those 80,000 miles were "buying" USD6500 or USD9500 worth of the J ticket, or a value per mile of 8 cents per mile/12 cents per mile based on whether you calculate from the discounted or full J value of the J seat. The miles were less valuable when you inevitably had to confirm two one-ways for a total mileage of 90,000. (I'm not counting taxes here to simplify things a bit.)

Now, I'd pay ~USD3200 for an R fare and use only 45,000 miles for the upgrade. Calculating in a similar manner, I end up with a value per mile of 12 cents (if you work from a discount J fare) to 18 cents (for a full J).

Assuming my math is right, the miles have become more valuable for the upgrades. BUT nothing in life is free. In exchange for giving us more value for the miles, CX requires us to shell out more cash. That will not be ideal for some pax, particularly the price-sensitive ones. But CX isn't necessarily interested in retaining price-sensitive pax through the loyalty scheme anyway. They can try to capture that pax via periodic sales like the fanfares when they need to fill planes on a particular route.

CX, in contrast to some North American carriers, appears to operate on the assumption that a loyalty program is only valuable to the airline if it encourages the loyalty of higher-revenue pax. I find that MPO is quite a valuable program in terms of the benefits they offer (lounge access, seat guarantee, etc). But they won't splash out like that on low-budget travelers.