If you look at almost any database management tool out there, vendor built or third party (SQL Mgmt Studio, TOAD, SQL Developer, etc.), which is what your Database Explorer is essentially competing with, they all provide the ability to add new fields and add new records without having to create SQL scripts to do it.
Your Database Explorer is already ready most of the way there, but with out those two operations, its like building a car and not adding a steering wheel or gas tank fill pipe. You have to do both the hard way or just keep going in the same direction.
If you are building a GUI tool, don't strip off two of the most commonly used operations that we have to use other tools to do on a constant daily basis when developing applications.