@Phelan-Kell
The landing spot is pretty important for turn 2 to threaten UK ships with the German airforce, without it your fighters range is extremely limited so the UK has more of a free hand. When and if Japan takes the money islands anyway then all the other Benelux territories become pro-allied too.
A rule to solve this might perhaps be that for each turn that Beneulux is not attacked, it either trades with the allies in some way, or simply adds some quantity of units to Belgium per turn (allowing it to spend all 15 of it’s cash on hand as if it was China would probably be ludicrous, thats 5 more infantry Germany would have to deal with so they would never ignore attacking it first turn and would make the whole point of the rule pointless. Hypothetically creating a new set of allied National Objectives might be a way to solve this.
BENELUX
Gateway to Europe
While neutral, and all original Benelux territories are controlled by Benelux 5 IPCs of collected income is distributed to each of United Kingdom, United States, ANZAC
However that again would probably just mean Germany attacks the first turn to get their own bonus, and rob the allies of this one.
You are correct in establishing the reason why Germany attacked the low countries, for a better attack path on to Paris. But that requires new mechanical special rules for the maginot line and whatnot. Even though the Maginot line was never intended to totally stop Germany, it was only designed to absorb an attack for 60 days while France could ramp up to full mobilization, so don’t treat it as an impenetrable line in your mind. Germany could very well ignore Belgium all game, and the Japanese can ignore it too and go for an attack on the USSR and get that new bonus.