Okay, sorry, let me spend some more time and give you an example.
One big problem with a unified dashboard is that not everything in your life should be monitored on the same frequency.
Here's one example: You probably need to check your email several times a day (if not, god bless you!) but checking your 401k balance several times a day is almost certainly harmful to your well-being. It probably doesn't make you happier; contemplating your money rarely does. Instead it will alternately make you worry (as every dip in the stock market causes nightmarish visions of a retirement spent in a cardboard box), or make you irrationally exuberant (as every good trading day makes you dream of buying a second home). The net effect is that it will subtly encourage you to trade, because if you don't trade your 401k is the most boring thing imaginable, and you feel the subconscious urge to tinker with it to make it do something. But trading is a disaster, because churning your investments makes other people rich at your expense, and because timing the market doesn't work, and telling yourself not to time the market usually doesn't work, either.
For much more on this topic see the work of e.g. William Bernstein (The Four Pillars of Investing, The Investor's Manifesto) or any of the so-called Bogleheads, or try Ramit Sethi:
Here's another example: The ideal amount of time to spend monitoring your weight is none, unless your weight is unhealthily large or is increasing significantly. (If you're prone to anorexia, a continuously updated dashboard showing your weight is potentially dangerous. You need to avoid playing that game.) And unless you're some sort of edge-case athlete, by no means should you monitor your weight daily: You should either weigh-in weekly, or weigh yourself daily but compute a running average (and have a deep understanding of what a running average is and why you're computing it). Otherwise day-to-day fluctuations are likely to destroy your confidence in your diet. (I'm told that, for this reason, Weight Watchers explicitly trains members to weigh-in weekly, not daily.)
So why can't your dashboard show different metrics each day? You can just configure the different widgets to show up at different frequencies.
Perhaps your 401k widget only shows up the first time you log in each quarter. Your weight tracking widget only shows up Monday morning. Your banking and monthly budgeting widget shows up daily. Your Amazon order shipping widget shows up only when you have an open order. Your meal plan widget shows up all the time.
You can choose which widgets you want. If you're poor and don't have a 401k, don't turn on the 401k widget. If you're rich and skinny and don't have problems maintaining either of those, don't turn on the budgeting and weight loss widgets. But a shared dashboard doesn't imply everything on the same frequency.
I already have a page where significant announcements show up at a wide variety of frequencies. It's called "webmail". Or an activity feed.
The point of a dashboard is that no navigation is required beyond turning your head and glancing. Dashboards are for things that you want to see by accident, or while waiting for a phone call. A widget that usually isn't there when you turn your head might as well not be on the dashboard at all. If you have to click to see it, it can be in a separate app or site. If you have to wait for a specific date and time to see it, it might just as well arrive in your mail, Twitter stream, or SMS.
The main difference in my eyes is that activity feeds and messages can create a backlog. The user experience isn't quite right either--different types of messages still look exactly the same. But different dashboard widgets could have radically different user experiences.
One big problem with a unified dashboard is that not everything in your life should be monitored on the same frequency.
Here's one example: You probably need to check your email several times a day (if not, god bless you!) but checking your 401k balance several times a day is almost certainly harmful to your well-being. It probably doesn't make you happier; contemplating your money rarely does. Instead it will alternately make you worry (as every dip in the stock market causes nightmarish visions of a retirement spent in a cardboard box), or make you irrationally exuberant (as every good trading day makes you dream of buying a second home). The net effect is that it will subtly encourage you to trade, because if you don't trade your 401k is the most boring thing imaginable, and you feel the subconscious urge to tinker with it to make it do something. But trading is a disaster, because churning your investments makes other people rich at your expense, and because timing the market doesn't work, and telling yourself not to time the market usually doesn't work, either.
For much more on this topic see the work of e.g. William Bernstein (The Four Pillars of Investing, The Investor's Manifesto) or any of the so-called Bogleheads, or try Ramit Sethi:
https://wordsofward.wordpress.com/2010/01/10/the-single-best...
Here's another example: The ideal amount of time to spend monitoring your weight is none, unless your weight is unhealthily large or is increasing significantly. (If you're prone to anorexia, a continuously updated dashboard showing your weight is potentially dangerous. You need to avoid playing that game.) And unless you're some sort of edge-case athlete, by no means should you monitor your weight daily: You should either weigh-in weekly, or weigh yourself daily but compute a running average (and have a deep understanding of what a running average is and why you're computing it). Otherwise day-to-day fluctuations are likely to destroy your confidence in your diet. (I'm told that, for this reason, Weight Watchers explicitly trains members to weigh-in weekly, not daily.)