It's not only about reduced visual clutter. It's about speed. You tend to use certain mobile apps dozens of times a day. A light, fast experience is crucial in this context
How does removing a helpful reminder allow me to work faster. IMO having this "visual clarity" on something that won't be used much other than the initial setup reduces speed. I'm not going to be adding new cards everyday. So only having the '+' causes me to pause and think, "What will this plus do again?"