I really don't get how this could be the case. I built something similar to this for my startup; it didn't have a pretty UI we could let our marketing team use

I really don't get how this could be the case. I built something similar to this for my startup; it didn't have a pretty UI we could let our marketing team use, but it also didn't cost nearly $0.10/text - it cost $0.01/text after we went into production, and was free while we were devving it. I would charge a fixed rate per month for the pretty front-end; that's what startups/marketing teams/etc. would sub for. I'd then charge for the variable SMS cost at nearly what you can pay a Twilio/Tropo for them, and make it a unified, uncapped plan.