We purchased when our resort opened, our son was 2 on his first trip to
DVC although he'd done a couple of trips to the parks prior to that. I took my daughter to Disney for the first time when she was 8 weeks old. Is having a washer/dryer at Disney when you have a baby more magical? Yes. Is the proximity to the parks something you'll be ridiculously grateful for (esp at BLT/BCV) with a baby? Yes.
That being said, the flip side of that coin is that:
Babies are insanely expensive, which makes purchasing more difficult (we'd saved up for several years before our first contract). Every kid is different. And kids change over time. There can be many not-magical parts of travelling and Disney with kids, too.
My DS15 was/is a great traveler, easygoing, napped anywhere. I have so many amazing pictures of him as a baby at the parks and at the resort. My DD4 ... well, she was okay as an infant, but as a toddler, oy. Let's just say she won't be going on any more DVC trips (or cruises) with us until she develops some more prefrontal cortex. Kids are individuals and don't always behave the way you'd expect, so even though we expect that taking them to the parks and to the resorts will be a magical experience ... it may not always be, and that's okay too. I'll still enjoy my DVC and plan on taking them both again when DD matures a bit more.
Maybe that's the best part of owning DVC with littles ... there will always be more trips in our future, more memories to be made. I take the same pictures of DS and my niece and nephew every trip on the balcony of the room, its become a tradition, its really cool to see the progression as they've grown (along with the trees in the background).