I didn't speak about those who subs later (it is normal that many want to check during one or two campaigns if this game is still for them). Was more thinking about people who do that for years never planning to sub.
Curious, do they bother you because you want to see the game grow permanently to ensure SE keeps this jalopy running, and people popping in only when free doesn't help that cause? Or do they bother you because during the free periods its crowded?
I've always seen SE's free periods in this game like giving away free heroin outside a methadone clinic. Most people who really want to get better will walk right past that offer. Some didn't really want to get better in the first place and jump on it. And some who did want to get better are just more susceptible to temptation and fall down the hole again. Its never about giving away something free out of the goodness of their heart. They're hoping maybe 5% of the people who "visit" end up sticking around.