Although the addition of touch sensors might improve upon the bots ability to detect obstacles when moving, in order to further improve upon the data collected, it would be useful to verify that the bot is actually moving when it thinks it is (i.e., when its motors are running).
The quick fix for this would be the addition of a free wheel on the front (instead of a skid plate), attached to a rotation sensor. Then it could be monitored to ensure that when the motors activated, motion is actually taking place (i.e., the bot isn't hung up on an obstacle). Some quick changes to the RCX explorer code could have the bot stop immediately when it detects that it's activated motors are not generating motion on the free wheel. This would be very helpful in low traction situations where the bot doesn't have enough grip on the surface to generate the force necessary to activate the touch sensors when pressing against an obstacle.
Again, this isn't possible with just the Mindstorms kit, as it does not include a rotation sensor.