The 2009 Xciting that I rode had linked brakes. I don't know if the current abs equipped models have
Them, but I know the non abs did. Their linked brakes were not even noticeable even on loose surfaces because they had a valve that didn't engage the front until the rear brakes were pressed pretty hard. And they actually applied a different set of front pads. I think I liked that system best.
The Piaggio BV350 has a system like that. The rear only actuates the front in heavy braking. I think the PCX is linked all the time. Someone on another forum who had a BV350 and his wife had a PCX commented that the linked brakes on the PCX were far more intrusive than on the BV350. The thing is that there are all kinds of variations of linked brakes out there but I'll bet that the majority of riders have no clue of the features of the system on the bike they are riding.
Harleys new linked brakes don't link if you hit the brakes below 25MPH. Some bikes are linked front to rear instead of rear to front and some are completely linked both ways with a complex set of valves to control the proportion. Linked brakes add cost and complexity to the system and often make the system a nightmare to bleed. Unlike ABS, linked brakes don't provide any anti skid protection.
one of the reasons I hate linked brakes is that when braking you have normally don't know how much of the braking is being done by each wheel. With a normal syystem you don't know exactly either but you can try stopping with just the front brake and get a feel for what hand pressure gives a certain amount of braking and then do the same with the rear. Or if braking with just the front and the adding some rear brake, all that additional braking comes from the rear.
While linked brakes may help beginners it will also make it more difficult for those beginners to learn how to brake properly.