that has always been my biggest complaint with TIXB. The TI was the only computer (that I'm aware of) that the majority of it's video capabilities were not accessible from it's advanced BASIC. which leads me to a question, if TI, when the memory expansion was attached, had moved all the tables to the main memory out of the VDP, would that have worked? that way all the VDP could been used for graphics. I know now that would cause a lot of compatibility issues but if it been done form the getgo would it worked?
as for the tables cutting into the main programming area, it wouldn't been any different than the other computers of the era.
The TABLES are mapped to the VDPs internal hardware. So really... only moving the program out to CPU RAM makes any sense.
A sort of desperate approach to use VRAM for an interpreted program in the first place.