They did, with the B+ in mid 2014, and the current Pi 2 with the same power design. The B+ and newer boards don't suffer the odd power supply issues that the older boards (even the B rev2) suffered.
And I'm not just rehashing what someone else said; I've had one each of the original B, a rev 2 B, a B+, and now a Pi 2. I've used the same power supply on all four, and on the B+ and Pi 2 I don't have any issues with hotplugging flash drives and wifi adapters whereas I did on the original and rev 2 models.
I've had my B+ running 24/7 since August as a webcam server to watch my dog in the back yard, and I've only had to reboot it once for an update. It's running a Microsoft USB-powered 720p webcam and an Edimax wifi adapter directly off of the built in USB, and it hasn't once had a power issue. I've had my Pi 2 running 24/7 since I got it a couple of weeks ago, as a "light" GNU/Linux workstation I can switch to and use when my main workstation is otherwise occupied. Again, no power issues on that board.
This reflects my experience as well. Not only did the B+ add a switching power supply, but there is proper USB power protection and soft-start as well.
Unless GP is referring to the flash problem of the RPi 2.0, which is readily solved by using a case, piece of tape, or an epoxy blob (which I imagine is what will be added to the manufacturing line eventually)
Many DC devices have capacitors on their power rails. When they are plugged in, they generate a huge current spike as the capacitors charge up (limited only by the resistance and inductance of the capacitors/wires). This is enough to overwhelm the power supply and cause a reset.
The solution is a current limiter of some sort. Sometimes this is as simple as initially powering the USB port through a resistor, watching until the USB voltage gets high enough, then switching over to a direct connection.
First I've heard of this; it does need a decent USB power supply, but that's a consequence of not shipping one and expecting the user to supply one of suitable quality.
I found the first model would sometimes brownout when trying to maximally utilize the ethernet. Which was not a big deal for a hobby device, but it did eliminate a number of possibilities.
And I'm not just rehashing what someone else said; I've had one each of the original B, a rev 2 B, a B+, and now a Pi 2. I've used the same power supply on all four, and on the B+ and Pi 2 I don't have any issues with hotplugging flash drives and wifi adapters whereas I did on the original and rev 2 models.
I've had my B+ running 24/7 since August as a webcam server to watch my dog in the back yard, and I've only had to reboot it once for an update. It's running a Microsoft USB-powered 720p webcam and an Edimax wifi adapter directly off of the built in USB, and it hasn't once had a power issue. I've had my Pi 2 running 24/7 since I got it a couple of weeks ago, as a "light" GNU/Linux workstation I can switch to and use when my main workstation is otherwise occupied. Again, no power issues on that board.