It is not unusual for landing aircraft to actually
aim for an exit at V3 if there's no traffic behind, in view of the long taxi-times from RW18R. In this case, it seems like the crew aimed at V3, but misjudged the braking effectiveness on that part of the runway, where the rain was pooring down. (Note 1: I doubt if the tower had reported braking action being less than GOOD. Note 2: V3 is not a high-speed exit; it is a rather steep turn that has been misjudged by other crews in the past.)
Here is a photo of another aircraft, landing on another runway on that same day; more photo's of the KLM incident are also shown there. Missing V3 is inconvenient for sure, but certainly not catastrophic, as the remaining runway to V4 still offers enough room to correct such a mistake.
It appears that this crew did exactly that: given the fact that the nosewheel entered the grass by only a few feet, their taxispeed at V4 must have been perfectly normal, even cautious. (I can imagine what this crew must have experienced: a few years ago I have personally witnessed a landing in Japan from the flightdeck, where a 150 ton aircraft started to skid uncontrollably towards the grass edge when vacating the runway. That happened at a staggering groundspeed of 4 (four!) whole knots, in conditions with taxiway braking action being reported MED. Differential thrust was needed to bring that aircraft back under control before the nosewheel could enter the grass.)
In case there's still any doubt: this KLM incident bears no resemblence with the BCN and Transavia accidents, since this airplane did
not skid off the runway during the landing phase. It skidded off a
taxiway during the
taxi phase.