Comparing the econo-geographic position of the MME site to the equivalent of a Trafford Park or Metro centre does not stack up. As you say, Teesside already has Teesside park, and that is struggling. The "success" of the Metro Centre and Trafford Park are because of close vicinity to a large populous hinterland combined with good road and public transport links. By contrast, the population of the whole of Tees Valley (if such a concept actually exists) is small vs Tyneside, and tiny cf to Manchester. Nor does Teesside have the financial and other service industries (nor the Nissans) that continue to buoy the Tyne and Wear conglomeration. It's the same basic underlying reasons why MME will always struggle as a scheduled air service airport.
And don't forget that the road system was a political sop after ONe had upset everybody by suggesting that MME should no longer be supported for pax services, and the region should concentrate solely on developing NCL. The political firestorm at the time was significant, but the economic logic was spot on.