i dont get the sense of this topic.
you can say the same thing even about the first wood upgrade (50 wood now instead of faster gathering in future).
every upgrade is an investment into the future, and there are always situtions where its better to mass units instead of click the upgrade. I don't see anything special for huskarls here...
I can find many situations that is worth to keep on castle massing huskarls, but I can't find even one situation where u wouldnt make double bit axe.