We don’t have one planned anytime soon, but would really like to do another one at some point 
I agree to some extent, but having something first isn’t necessarily the benchmark for loyalty (think of all the people who couldn’t make it to our offices in London for the first early Alpha rollouts, but who would have loved to try Monzo out.) Giving priority to those who use the card more regularly makes similar assumptions that the most ‘loyal customers’ all have the same spending habits. There are plenty of reasons someone may wish to split their budget and monthly spend between their Monzo card and another account.
I don’t think it should be up to us who is ‘worthy’ of investing, which is why random selection seemed like the most democratic way to do this.