For me (personally) it is no underestimation, but realism. And of course I hope the Dutch will win the 20 golds Gracenote predicts. But I don't see that happen. And however, 30-35 medals is quite a lot?
A lot of medals on World Champs have been won while favourites didn't compete, like in swimming (4x100 free / Van Rouwendaal / Schouten) and in athletics (4x400, Bol). I understand the Gracenote-prediction, but gold for Van Rouwendaal, Schouten, the 4x100 free ... not in a million years. And I don't see Bol - competing finally against Sydney McLL again - winning gold either.
On the other hand we have some big favourites, like Lavreysen (track cycling), Florijn (rowing) and the hockey women. So yeah, we will definitely win some golds, but I think most of the medals will be silver and bronze, which still is very good for a small country like Netherlands.
And who knows, when everything turns well, we maybe can surprise. Until then I'll keep the expectations low, otherwise it will only be disappointing.