We design our UIs to be functional, because of the aforementioned. But the users have absolutely no idea what is going on under the hood. The UI is THE product to them.
So as a fellow founder/architect/... i strongly urge you to hire a professional designer who will create a CONSISTENT and INTUITIVE user interface. YOU will not see much value in that but your users WILL.
Personal anecdote, when I launched my last project, Gethly.com, I asked a friend to do some user stuff and give me some feedback. I very quickly realised that I had a lot of work ahead of me when he told me he had no idea how to do absolutely basic things because of the wording used in the UI(nomenclature can become a problem) or click a link that was staring him right in the face was completely invisible to him. Again, I call this "founder's blindness" type of thing where we are incapable of seeing our own work through user's eyes as we have too much knowledge of the whole thing and cannot even comprehend how someone would be unable to do a, in our eyes, most basic thing.