I think it’s more than the tech. As I mentioned here…
… Monzo probably have to do more technical integration than other banks because they have an in-house payments processor. Now, you might be right and the actual effort minimal in terms of code changes or whatever (although I believe there’s probably more to it than you think) - but even if you are I imagine there’s time for compliance, audit, paperwork etc.
And then there’s business priorities for Monzo. Rightly or wrongly, I think they’ve made it clear that they believe other functionality is more important and therefore prioritised. While it’s great that we can talk directly to Monzo folk, we need to remember that this isn’t a democracy and that, ultimately, Monzo will make their own decisions (though fortunately having heard and considered our feedback).
Ultimately, if something like Samsung Pay is important to you, then there are other options out there. I’m on record as a Fitbit user and while I’d love Monzo to support it, I know that that’s unlikely. I did, though, own a Starling account just for that purpose - but I’ve only ever used it a single digit number of times, and then only to try it out (or in emergencies). Your mileage, of course, may vary…