"Or just government spending logic?"

I believe it's just this. Too much of our military's decision making is influenced by the contractors that build the weapons. The F-35 is the largest single military purchase we've ever done. Too many people would lose too much if the program was abandoned, so the politicians involved cannibalized budgets from things that could be a competitor.

"Interesting also that there is a ban on export of F-22 (even to good friends like UK/etc) while F-35 is supposed to be available for export."

It is. I think that may be partly to do with materials used on the F-22, particularly the coatings. It has to be 'repainted' every so often in a very precise way, so to sell them to allies we'd also have to transfer knowledge of the materials and process.

It's worth noting that many of the customers that were in line to buy the F-35 have pulled out or are at least voicing concerns in their media.

I thought the issue was the F-35 could be multirole, and F-22 couldn't, so they needed to replace F-16/F-18/A-10/etc., which the F-22 couldn't do.

I still think manned combat aircraft are probably on the way out, and absent a current threat, we should be life-extending our existing aircraft, spending 10% of F-35/F-22/etc. on combat UAVs, and end up with ultimately better capability (like, 100x more UAVs than manned aircraft, the ability to go on one-way missions, etc.) Kills the aviator officer career path, though.