The lack of modern design air force aircraft types at the start of the war has perhaps more to do with the idea in the 1938s, 39s, that war was far away so there was not really a need to spend money in advanced designs. But around 39 ideas changed, and a frenzy came along to design and build modern types. But by then it was already to late, the German built-up was not to be overtaken.
The story goes, that the small Dutch airforce wanted desparately modern fighters and bombers, but all the major foreign manufacturers were busy supplying their own countries, so the Dutch turned to acquiring anti aircraft guns instead, by the hundreds. The Nazi's didn't realise that and the 700 or so air force of Ju 52's used in the occupation of the Low Countries was suddenly decimated. That force was supposed to be used for the invasion of the UK.