The board is aimed for use in custom PCB's so the user can either solder a USB connector onto their board, have some test pads and use pogo pins to program the board, or they can just cut an old USB cable and solder this directly to the USB pads on the board.
That is a reasonable point/idea, no onboard USB, allows it to be small/compact, and optimised for installation on someones custom PCB.
On the other hand, your board would have had more potential usage options and hence potential customers/market-share. If it had some kind of direct USB connector, or option via PCB pads and/or two different versions, one with and one without a fitted USB connector.
I suppose time will tell, if the price point you have set, and it being somewhat/partly USB less (as it stands), matters or not, by the success of your currently active kickstarter campaign.
I don't think the price is too unreasonable, although I still think it is on the rather high side, especially for mass/bulk sales. Because, although the Raspberry PI PICO (standard edition), is around $4/£3.60+, its smaller decedents (by other manufactures, but still the RP2040 PICO chip/mcu), are around double or more that price (e.g. $8.50), and some even more specialized versions are much higher priced, still.
I.e. Although you can get cheap mcu boards for say $2 (prices seem to have been going up though, in recent times). The price rapidly increases (e.g. doubles, for each improvement. i.e. x2 quality, x4 quality+Arm, x8 price quality+Decent-spec'd-Arm+tiny-size, etc etc), as you go for quality (i.e. NOT cheap Chinese), Arm rather than 8 bit Arduino AVR series, Tiny size, various specialized versions, e.g. Includes wi-fi.
Your main selling points seem to be somewhat low power consumption (without having to perform time-consuming and sometimes difficult software optimizations, to use various low power sleep and similar modes), at 10mA (i.e. battery powered and wanting reasonable battery life). Reasonable capabilities being an Arm, and Arduino compatibility. Plus tiny size.