It seriously took me years of careful tweaking to get my feed (and lists) where I want them. Now Twitter is absolutely incredible; Twitter lets you be in a room with anybody in the world you want to. That's really, really cool. For me, that's startup legends and tech geniuses. I not only get to see what they're saying, but often what they're reading and thinking about. Because of that I wanted to see the feeds of some of the top tech investors look like, so I created them in lists. They're fascinating to watch (lists are here http://theireyes.austenallred.com/pages/viewlist)
But I look at so many of my friends who don't use it, or who have an account and don't log in, and it's almost always because they haven't taken the time to follow the right people. That's hard to do. Facebook is easy - my grandma knows me so she'll accept my friend request. Twitter, by its nature, forces you to be proactive in creating and culling that list. That's an action that most people don't take.
So Twitter is trying something new - what if we put together lists of what people want and had those available as the logged-out homepage, letting people quickly get involved? It's an admirable effort, but look at the categories available: It recommends I search for stuff like #NationalDayOfPrayer or #BadBloodMusicVideo. The top categories right now are literally politicians, high-end fashion designers, nascar drivers, and hotels/travel agents. I get that they're trying to show you variety, but talk about shots in the dark.
I don't know what the solution is. But I think Twitter's biggest problem is that it simply takes too much work before anyone gains value from Twitter. There are a lot of people on this planet who will never put that much work in before expecting something of value back out of a service.