In order to understand why this is such a revolutionary proposal, we must turn our eye to art. 55 of the Dutch Constitution:
Article 55These provincial parliaments are the descendants of the Estates that held sovereignty in the time of the republic. (Hence: Estates-General, being the gathering of representatives sent by the provincial Estates.) At the time, there were seven of them, now there are twelve. Their seat numbers are as follows:
The members of the First Chamber shall be chosen by the members of the provincial councils. The election shall take place not more than three months after the election of the members of the provincial councils except in the event of the dissolution of the Chamber.
For a total of 566 individuals who are eligible to vote in an election for the Senate.
That is to say, 566 people elect 75 senators, who need about 7½ votes to be elected. In such circumstances, it doesn't really make sense to disband parliament and call a new election, even if there are a few loose cannons that the parties might want to get rid of. That is why such a snap Senate election hasn't been done since 1904. However, in this case there are several special circumstances that make it a tempting idea.
During the last Senate elections in 2011 there was a couple of unfortunate SNAFUs. One D'66 parliamentarian accidentally voted with a pencil of the wrong colour, making his vote invalid. Another D'66 voter voted strategically - in an election like this it can be smart to vote for the "wrong" party - and got his math wrong. Then there was some creative horse trading in Zeeland that probably wouldn't be repeated this time. But most importantly, all over the country provincial MPs of Wilders's PVV have left the party. Since their number is eight, they theoretically add up to an entire Senate seat, assuming they wouldn't still vote for the PVV.
Adding this mess together means that a snap Senate election would probably result in one fewer seat for the PVV, with that seat ending up with Prime-Minister Rutte's VVD if these provincial parliamentarians vote for the logical alternative, or with D'66 if they vote in a less coherent manner. Either way, a Senate seat is transferred from a flank party to the centre. So I say: Let's do it!