Suspected this was still true as I have done it a lot over the past decade, but since the pandemic, I haven't flown BA in nearly two years. I was afraid something had changed!

While it is true that pricing anomalies occasionally occur where WTP can be more expensive than CW depending on the buckets available, in the vast majority of cases, I've found WTP prices (looking mostly at JFK to routes other than LHR in the UK and to mainland Europe regularly around $1000 while CW is more likely $2200. The occasional sale, whether advertised or not as such, may bring WTP down to $800 while CW goes for $1600, but since it's rare that sales on WTP and CW occur at the same time, it is possible for CW to cost $1600 while WTP has crept closer to $1500. Under those circumstances, I would agree that using Avios to upgrade is a poor value, but from my experience, it's an excellent value in almost all other circumstances.