Except that LS never made it to more than 10/20% of the troops and most legions fighting on the front preferred the much less maintenance intensive hamata.

Also, comitanenses weren't any weaker than the older legions, the problem is that they spent more time fighting internal enemies than external ones.
ecoThe roman military kept excellent quality as long as the economy could support them, after that everything went downhill in the west, the east stood for another millennia.