The old reminder schedule of 2 weeks, 1 week and 1 day worked well. It did because the classic rule of marketing is three contacts. As as happened many times in the past, if it's not broke, Meetup has decided to fix it (And were organizers asked about what they wanted or what works best for them? If so, I would like to see the survey results. If not, why weren't the people who pay you money and keep your business running consulted?)

A first reminder of 6 days before is not a good idea because most people plan with a longer time frame and could easily be committed by then. Reminders should also NEVER be sent out on Fridays afternoon/evenings. A lot of people use their work email addresses and this means they would get their first notice of the meeting from Meetup when they come back to work on Monday -- 3 days before a meeting.

I realize that Meetup is claiming that it tested the 2 week notice and didn't get "enough" RSVPs. This is not exactly surprising since the first contact is the least effective according to marketing theory. The third contact seals the deal.

Why not let the organizer choose which days they want the automated announcement to go out? So if the want 14 days, 7 days and 1 day, they can have it. Organizers know their groups and what works best for them, not Meetup HQ -- and hopefully one day Meetup HQ will realize this.