Thinking there should be a distinct iOS version: sure, okay, that is at least a sane position to take. A naive position, but a sane one.
It's very rare to see a multiplayer game with distinct implementations that interoperate with each other, because the cost of developing it is so high, and the historical success rate of making it work correctly is so low.
This company is making a very wise choice by making an HTML5 platform they can use everywhere.
I dunno, just thinking of Words With Friends... I like how I can play it on my Android phone, or I can go home and play it on my computer, against people on computers and iPads.
I will say that as an owner of a Kindle Fire and an Android phone, I would love to see a native Android version of the game rather than a web interface. Isotropic just barely works on my Fire; it tends to disconnect fairly often and it's pretty frustrating to use, but it can be done. It's been my experience that web interfaces/in-browser apps just don't work that well on mobile devices. So hey, chalk me up as one of those naive people who wants a native app rather than accessing it through a browser.
I suppose since Dominion is not a time-sensitive action game, a browser app COULD work. If they put some good effort into it, I could see it being totally usable on a tablet or phone, much more so than Isotropic. The other advantage to a browser game is that, assuming it is paid or has a paid option, you wouldn't have to pay more than once for multiple devices.