Two different uses - I see the Lance as a typical weekender or vacation use camper. The Nash/Arctic Fox products ride on beefy frames fabricated by Nash and have a coach that's built for true 4-season use. Not everyone needs a Nash that is full-weight when a Lance will serve the owner who uses it as a vacationer.
The holes you mentioned are typical of the Norco frame which is stamped steel with a torsion suspension.
2013 Jayco Eagle 334RBTS
Disclaimer for the daft: Don't confuse my opinion with facts.