Regalk, you one-eyed?
Chipsets going through revisions is a very common thing - however most of these revisions just fix bugs, and don't bring new features or performance enhancements. VIA actually has a pretty good track record in that regard.
It's not like others don't do it. Intel BX wasn't good until revision 3, its south bridge PIIX4 was later revised to PIIX4e to fix a major problem in power management. i810 wouldn't work with 100 MHz P-II, i810E followed on its footsteps. Its first revision ICH south bridge didn't quite work right either.
To set the record straight, what did we have from VIA so far ...
Apollo Pro: P6 chipset
Pro+: revamped for P-II
Pro-BX: pinout changed to be pin-to-pin Intel BX compatible. Never marketed.
Pro-133: pinout changed to be almost Intel BX. 133 MHz RAM and FSB.
Pro-133A: AGP 4x added
Pro-133T: CPU bus changed for Tualatin compatibility.
Pro-266: V-Link instead of PCI. DDR RAM bus.
Nothing wrong with Pro-133. In fact, it's still widely used because you can use one common board for Pro-133 and 596B south bridge or for Intel BX and PIIX4e.
To Athlon.
KX133 - Slot-A chipset.
KT133 - socket-A chipset, CPU bus adapted to AMD's sudden electrical change
KT133A - 133 MHz CPU bus added.
KT266 - DDR RAM capability added. South bridge bus changed from PCI to V-Link.
KT266A - new faster RAM controller
Nothing inherently wrong with any of those. KT266 wasn't exactly lousy to start with, KT266A is just plain amazingly fast.
South bridges ...
586 - first one from early Pentium days
586A - USB added
586B - UDMA33 added, power management added
596 - moved to BGA package, PIIX4 pinout, ACPI power management
596A - pinout slightly changed to "almost-PIIX4"
596B - IDE updated to UDMA66
686A - include super-IO, more power management, two more USB, sound and modem engine
686B - IDE updated to UDMA100.
8231 - ISA bus removed, six USB, four-channel sound, LAN MAC added.
None of them has any major bugs - it's only that the packed 686B chokes on the PCI bus which is too slow for all the integrated stuff. Which is why they moved to ...
8233 - V-Link bus instead of PCI. PCI bridge integrated to support PCI slots.
8233C - alternate version with 3COM LAN MAC instead of VIA.
Interested in similar lists for Intel, SiS or ALi? You'll get just as many chips listed, with a very similar history. Feature additions, new busses, new chip packages, electrical changes to adapt to new CPUs, and of course bug fixes.
regards, Peter