A depressingly Network Rail - esque answer. Network Rail has become this incredibly defensive organisation that spends most of its time defending the status quo. There are a small number of good people but they are operating against a torrent of institutional inertia.
Your last two sentences reveal a basic lack of understanding. British infrastructure utilisation rates - tph on plain line sections with mixed stopping patterns, and platform utilisation rates are incredibly similar to Dutch ones. The Dutch network isn't awash with fancy grade separations either (theirs is somewhat better than ours, but not wildly so). What the Dutch are good at are operating services in ways the infrastructure is designed to, and recognising that passengers changing trains is more efficient than trains changing tracks, as long as you make make changes simple, predictable and reliable. At New Street that means splitting it into two independent parts, and operating each part as outer roads for through and inner roads for terminating.
Rotterdam - Arneham requires a change. Eindhoven - Amersfoort requires a change. These cross-Utrecht journeys are incredibly similar to cross-Birmingham ones.
Most Train Service Specifications (TSRs) express service levels in terms of tph (or implied). It's in Network Rail's own interest to organise all the TOC's TSRs into a common symmetry and a takt structure. This means you only need to work one half hour and repeat - it saves work for itself. Even SNCF Reseaux attempts to put TOC requests into a national symmetrical takt, so does Italy's RFI. Yes, there are aspects of the TSR or TOC demands the Network Code does not protect - like half-hourly at departure for combined hourly services (like the hourly fast and slow London - Edinburgh). Network Rail as the infrastructure operator should exercise technical leadership by insisting on symmetry (if the Down wants to depart King's Cross half hourly, the Up can't depart Edinburgh half hourly). Similarly the Network Code doesn't care about departure times, despite TOCs wanting 00/30 departures for their flagship services. Abbeyhill Junction means that the optimum King's Cross departures for the Edinburgh services are xx57/27, not 00/30.
The inertia isn't entirely Network Rail's fault. It had to accommodate silly routings from TOC access requests. There has been weak and chaotic political leadership in the last 10 years. Nonetheless, Network Rail has a remit for long-term strategic planning - simply passively receiving access requests and tinkering the graph isn't fulfilling that strategic remit. Netherland's Prorail publish maps like
this to start conversations and guide TOCs and politicians on what is and isn't possible and sensible. Network Rail used to do things like that with the Route Utilisation Strategies (RUSs). Network Rail's competence in thought leadership and long-term planning has deteriorated since the RUS days. With DfT TOCs either publicly owned or as management contracts, Network Rail is in that unique position of having a technical helicopter view of the timetable and advising the DfT and its political masters of the technical intricacies. As the predecessor organisation of GBR, Network Rail is demonstrating a complete lack of readiness to step up.