what? did you want real answers? those were incredibly rhetorical questions.

fine

why hunt for better? because better things will keep coming out. whether its community day exclusive moves or an entire new generation of pokemon with higher stats and better moves.

why do more registeel raids? you shouldn't. nobody is asking you to do more than 1 for a dex entry. you can do more to get more registeel candy or more rare candy. the IV increasing mechanic can require stardust and candy as a cost. you should also be doing them to help other people in your community get them for their dex entries, and also get generic raid rewards for it.

why keep looking for machops? to trade for lucky ones. not sure why you'd want 90% IV ones you catch yourself when the new mechanic greatly benefits trading for them, but you can play however you like.