Well, first of all, writing a programming language was a very interesting challenge. We were fascinated by all aspects of language interpretation. While text of a program is easy to understand by humans, computer must convert it into a form which it can be understand before any emulation or compilation can begin. This task is quite complicated from a program point of view.
Second: the more we advanced on the project, the more we discovered that most of the characteristics of thinBasic were unique or not present in other basic interpreters. At least not present in the same product.
So, we decided to go on with the project.