I suspect part of the foresight was exactly to create this situation, where the problem is framed as lack of transmission capacity. Because the alternative - building transmission capacity before it was needed - is even less politically feasible. Public money can only be spent when the need is so blatant it can no longer be ignored, and then everyone sits around and says "well why didn't we do that sooner".
Of course, the same arguments killed the construction of onshore wind in England, which would have prevented needing the new powerlines (or at least not so much).
From the article, it looks like the problem is partially caused by significant parts of the transmission network being temporarily shut down due to ongoing upgrades. These could probably have been started slightly sooner, but they are already underway, so I don't think your point is weel supported.
Except that if those upgrades had been started 10 years earlier then there would have been lower demand (10 years less growth in demand). The reductions in capacity would have had a much lower effect on prices.
