That's the trap. If they want to succeed they have to accommodate a wider range of use-cases but not without complicating the product line-up.
The problem is that phones are a way bigger deal than computers. If they made but one laptop model it'd be ridiculous. Having one or two phones isn't a big deal. Twenty or, like Samsung in its heyday, two hundred is a problem.
As an aside, they seem to be headed back in this direction once again, with what appears to be 5 different-but-essentially-the-same phones coming out on the market this september.
And a whole bunch of wildly priced desktops and laptops that don't seem to consider anything but the bottom line.