There's more than meets the eye as usual.
Different people, different cruising styles, different climates, different budgets, different boats, and other issues all affect genset issues.
The worst reason to not run one is the fear running the genset wears it out...to the point where decay is beating usage.
Other than that....cruising in general needs a rough plan on how it is gonna go and the genset is just one factor. But there will be times when it can't be run...and what are the alternatives and times where you don't want to run it for a variety of reasons.
For serious long term cruisers...both the main engine(s) and the genset will need rebuild/replace.
Based on my style cruising and trying to space major capital replacements/purchases as far apart as possible gives me a rough idea of either how much I can run them or when will they need replacing based on use.
I think running one hard once a week is good if you aren't laying up the boat for more than several months...more than that and I would follow the recommended long term storage directions.