I think one important aspect of DBW in the S2000 has not been covered - emissions

The DBW in 06+ S2000s allows the engine to hold the throttle open for a split second when you clutch in to shift preventing the engine from going rich for a split second. This allows the 06+ S2000 to comply with Tier II LEV regulations. In other words, it is a LEV-II vehicle, whereas the 00-05 S2000s are LEV-I vehicles.

The DBW system has no lag, and thats just my 2 cents from having driven approx. 10 different S2000s, both AP1s and AP2s with and without DBW.

As for VSA - there is an off button. During track and autox sessions, the car displays no stability intervention, and the system is a boon in foul weather daily driving conditions.

 

VSA doesn't require DBW. The newer VSA systems may, but the 2001-2003 CL-S (including the CL-S 6MT) and 2002-2003 TL-S all have cable throttles and VSA. Traction control was used on older cars as well like the RL, and I don't think they used DBW.

So Honda/Acura had a method on their older cars to control throttle without DBW.

Honda could have probably implemented VSA without using DBW, but it may have been easier or more practical to use DBW. I guess it could be the LEV II ratings like vishnus11 said.

 

can the DBW get removed??

 

I have experienced one failure of a throttle cable (1966 Plymouth). The cable sheath very suddenly separated, which had the effect of jamming the throttle in fairly wide open position without any warning. It was not pleasant. Hopefully, such a failure mode is not possible with DBW. After all, it is controlled by software, and everyone knows that computer programmers never make mistakes.