My hubs seem to get traffic in streaks. They will get a lot of traffic and then it will drop off as suddenly as it started. They will sometimes reach 'idle status' before another streak of traffic comes along, sometimes the traffic comes just in the nick of time before they are again idled.
When the next streak of traffic comes along, if it's strong enough, the hub will be taken out of 'idle status,' by HP, even though nothing has changed except for the passage of time. I sometimes think they will be thread bare from all the inning and outing of idled-ness.
We can always improve our hubs, and editing should be done ad nauseum since we all make spelling errors and the like from time to time, but traffic is what determines how long a hub will be featured. Spend your time promoting your hubs and doing everything possible to that end.
Make sure you put a good title on your hub that people searching for the info in that hub will put into search boxes to find that info. Splashy magazine style titles are very satisfying and look great, but no one puts that sort of thing in a search box when looking for information. Think what words you would use if you were looking for the info in your hub and put those words into the title. If the splashy title is so important to you, then put it in the headings above the capsules, or into the body of the hub.
I don't plan to retire any of my hubs. I keep the little box checked on my profile page that makes them available to anyone who wants to read them. Even HP has said that just because a hub is idled doesn't mean it's useless. The advertising is still on it. Friends, family, other hubbers, lots of people may want to read those hubs and like I said, why dump it when the next traffic streak is just around the corner? Promote the hub. Promote it everywhere you can think of and to everyone you know by every means.
Idled hubs do no harm just sitting there all fizzled, as you say. So why lose sleep over them? Why not, as Wrylilt has said more than once, move on and write a new hub that may be more popular? Meanwhile the idled hub may get the occasional view, or like mine, the streaks of traffic from time to time.
It seems to me from reading various comments about idled hubs that an awful lot of energy is being expended on HP agonizing over idled hubs. Put that energy to work doing something positive. Again, promote your hubs, and write new hubs.