Likely your suspension wasn't put together correctly the last time.
If it was, then 'flimsy' isn't the problem, it's lack of maintenance that was the culprit.
It's easy on the oem linkage to tighten the pull rods against the shoulder of the bolt as opposed to correctly having the shoulder of the bolt go through the rod. After a couple of bumps the rod gets knocked off the shoulder of the bolt, then you have enough slop in the assembly that will very quickly elongate the pull rod holes.
Yes, there are aftermarket parts that are 'not so flimsy.'
Again, it's not a matter of flimsy. If you had an aftermarket rod in the same put-together state as the oem rods, they would get wasted, too.
But, the aftermarket rods I use (Devol makes a nice set that is adustable in length too!) require KX250 bolts that are considerably longer than the OEM bolts. Primarily that is because the Devol rods are aluminum and so are quite a bit thicker.
BTW, the Devol rods do not come with the required bolts and shims required for their installation. The Devol folks have the part numbers you need, but they don't (didn't awhile back anyway) sell you the hardware. That will have to come from your local Kawi dealer or a web site like RonAyers.
The lack of maintenance part would figure in if the assembly was so in need of service that it effectively had no bearings in it at all. The force of the rear wheel banging on it all the time could not only take out the pull rods, but take out the entire unitrack knuckle as well!
In any case, be prepared to replace the bottom shock mount bearing. It's toast most of the time. The Kawi replacement bearing isn't worth a hoot..the pins are sloppy-loose in the cage just aching to fail. And fail they do!
Use the best grease you can get. Belray grease for marine applications has been reportedly used to good effect. Your one-each moly-di-sul chassis lube is a waste of time and effort.
I use a Hydrotex product which is a combination of a bunch of stuff...a semi-syn grease called Hydrosyn. It's expensive...about $10 a tube, but it works!
Besides that, it's a pretty color!!
Gotta have that!!