History has shown that if you make it easy to access something, people will generally prefer to access it legally rather than using piracy, because most people are willing to pay for something if they have the option and if it's relatively affordable. Trying to stop piracy doesn't help sales, let alone hypothetical future sales, so trying to stop roms of older games won't help them make more profit when they relaunch/re-release older games on newer consoles. So it's still pointless. Not to mention that people playing those older games in the meantime keeps them in the public consciousness longer and so more people are likely to know about them, hear about them, and want to buy them when they're available through official channels.

Found the bootlicker!

Would buying used games also undermine their efforts to capitalize on relaunching a franchise?

That's a good "what if" there, but no.

The mental gymnastics you people play to justify copyright infringement is amazing.

I don't need mental gymnastics. All I need are ROMs.