Right, you just explained WHY they shouldn't focus on catering to the 1% of the "hardcore." Many people sub for 1 or 2 months and leave, agreed. So maybe if they cater to them, instead of the 1% of the population that resubscribes consistently, they'll sub for months to come! Fact is, the uber hardcore progression raider is a sheep. They will consistently flock to the most juicy content and pay their subscription. Evidence: see every so called hardcore MMO released in the past 15 years.
I started to type out a long winded response stating my opinion differently, then realized that more than anything, nothing you nor I say is a fact, it's all just our opinions or generalizations that aren't going to be true in even most situations, just some.
What it comes down to, is that they can make the hardcore progression guilds happy by keeping patches to a fixed schedule of say, always being on a Tuesday, and still provide everyone else with what they want, IE bug fixes. It's not one or the other.