To a visually oriented communicator with lots of experience crafting written messages, your plain text format is very limiting and uninteresting. Its like texting. Good for a quick note to some close friends like “let’s grab a beer” but not practical for conveying complexity or attracting attention.
You appear to be going after the users and organizers who don’t have a desktop computer, only a smart-phone. That chops off the high end of your niche. But, that’s not necessary. You can have it both ways. Your recent merger gives you the needed resources.
If you don’t grab the full opportunity, someone else will. Be smart. Don’t waste all that Meetup goodwill.