This discussion has come up many times in the PMUA forum regarding E+. I think you can easily make the comparison to ELR.

Many had mentioned...

• "the flight was empty, what the big deal",
• "no elites were there, the whole row was empty, what would it hurt".

and so on,

But it is my firm belief, protecting those seats:

• Gives the passenger better understanding of the benefit (and they may pay the $$$ next time).
• Makes it easier on future flight crews.... "what do you mean I can sit here, they let me do it last time".