I found Erica's opinions valuable in terms of thinking through iOS 11's multitasking UI redesign, even though I don't agree with her conclusion (that the new design is worse overall). Her concerns about whether it serves all users are commendable. In general it's critical to consider all points of view on subjective decisions. If you don't think about the other side of an argument, you haven't really thought through a problem.
I think the new multitasking UI is awesome and necessary for implementing Spaces, but Erica correctly identifies many of the downsides to the redesign. All of her points are valid, but it's also worth noting that none of these features are strictly necessary to use an iPad. If users never discover the multitasking UI in the first place, they can continue using the iPad exactly the same as always.
All engineering involves making tradeoffs. The cost of not implementing this more power user-friendly redesign would be the iPad continuing to stagnate. Tablets need to continuing evolving to do more than phones, and they've arguably taken far too long to do so. The increase in complexity is a necessary tradeoff in order to make tablets more valuable in their own right. That's not to say there isn't definitely a lot of room for improvement with this new UI, though, of course.
I personally like that a side effect of the new UI is that users can no longer easily swipe away apps, hurting performance and battery life even though they are often actually trying to improve battery life. The previous UI probably would have made it too easy to accidentally swipe away a Space that users had bothered to set up.
iOS 11's new Control Center is also pretty much exactly what I wanted to improve watchOS: an untruncated vertical scrolling list. Having to perform separate swipes to access multitasking and Control Center would be more confusing and time-consuming for users. The unified bottom swipe not only encourages more frequent multitasking, but it also provides a simplification of the previous four-finger gesture shortcut. There are always many aspects to consider regarding accessibility.
Design is hard.