The AK101 is mainly for the export market, the AK74M, is still the mainstay weapon of the Russian Federation.
http://en.wikipedia.org/wiki/AK-101
On a comparison between the AK47 and the M16, one can see the completely different and diverse thinking behind the design and conception of both:
http://en.wikipedia.org/wiki/Comparison_of_the_AK-47_and_M16
WRT the R1-FN that we used initially, it was decided it was the best out of 3 that were tested for the old SADF, the 3 were the G3, the Armalite AR-10, and the FN FAL. SA was also given permission to produce the FN FAL under licence, so it became the weapon of choice, until the adaption of the Galil/R4.
http://en.wikipedia.org/wiki/FN_FAL
The R1 was a very good rifle
for its time, however there were a number of drawbacks:
Weight,WRT to carrying in the ready position
Running through undergrowth and bush, was sometimes problematic due to its length.
Mounting and dismounting from vehicles due to length.
Not suitable for close combat, and urban warfare, ponderous and heavy to keep in the shouder when moving, length tendered to make it waver a lot trying to fire and move.
Some models compensated for that by coming out with a folding stock, and slightly shorter barrel, but they were not enough to become standard issue.
So the Galil/R4 was adapted, being lighter and easier to handle.