This does seem to be a surprising "disaster" for Dutch public transport.
It is a long time since I've been to the Netherlands so have lost touch
with how the various main city networks are faring. I have read a
little about Randstadrail and know broadly what it was trying to
achieve. What has the local reaction been like to the problems that have
arisen? Shock, outrage, resignation, something altogether more Dutch?

The systems are quite okay, really. I don't think you could say
anything is really getting worse. But the improvements that had been
planned have all been delivered late, went overbudget and have had
introductory problems.
This is true the five big projects; Randstadrail (still not ready,
detrainments have put the whole thing to a halt), HSL-Zuid (still not
ready, overbudget), Betuweroute (still not ready, overbudget) and the
North-South line in Amsterdam (overbudget, due date has already been
set back) and the OV-Chipkaart (as described above, going to be
introduced late as well). I'm sure we'll see the actual improvements
in the end, but these things aren't making railways any more popular
with the general public, and I can't see it helping with upcoming
projects. The Hanzelijn, although only in its planning stages, has
secured its money and it looks like that will be going well. So far.

On a brighter note, the completely new timetable that was introduced
in December has actually been a succes, and not the big disaster that
many had thought it would be.

(I don't live there anymore now, but I try and keep up to date.