Why not 5 Type-A?
A third Type-A is redundant. Any case where you need more than 2 is served nearly as well with a hub, which are incredibly common. As you said, Type-A is very cheap.
example: A TB3 SSD and a Type-C Alt-mode adapter.
And there's a reason you haven't found any Type-A to Type-C (receptacle) adapters. Such an adapter is not permitted in the spec, as it can allow consumers to engineer dangerous setups (you've heard of non-compliant cables frying devices, yes?). So while we can always adapt a Type-C receptacle to a Type-A (For a measly $0.99), the reverse is not true. Type-C, afterall, is not 'just' another port for USB 3.1 gen 2. It exists alongside that standard, because it actually has more pins available than Type-A, part of the reason TB3 can exist as it does.
But this is rather pointless, neither of us is going to convince the other I think.
The HDMI port poll made it clear, however, that nobody wanted to sacrifice the Type-C port in favor of the HDMI. Overwhelmingly the Eve Community either wanted TB3/Type-C ports or TB3/Type-C/HDMI all together. If people didn't wanna lose the port in favor of HDMI, why would they wanna switch it to Type-A? I think I saw the poll for that which indicated it was 50/50 split on ditching second Type-A for HDMI port. Transitive law in effect.