Just saying, not really comparing similar systems.Because that's the only way to expand any current Mac. On the PC side one would buy a system which can accommodate these things internally making TB3 much less important.
It's like comparing two towers one with 8x PCie slots and one with 3x and complaining that the 8x slotted one is more expensive. Well, duh.
I really don't mind external expansion frankly. the Mini will be tucked behind a desk, whether the drive is in a box cabled or mounted directly to the board doesn't make a difference. In fact in my case, I'd have it in a fast case cabled anyway so i can take it with me without dealing with file transfers.