Small companies make easy targets. By limiting mags to >10, they don't run any risk of coming up on the wrong agency's radar for hi-cap mags. Some states, like mine, have tricky regulations on mags over a capacity of 10.The Kel-Tec Sub 2000 is designed to accept the hi cap glock mags why can't hp do something like that? Kel-Tec Sub 2000 is in the same price range.
I don't know for sure if this is Hi-Point's exact reasoning, but I have a strong feeling it is.