DSEG7 uses some lower case forms (e.g. for "b", "n", "t") to avoid letter shapes which are impossible to represent on a 7-segment display (like "N"), or which would be ambiguous (e.g. "B" / "8").
You still can't represent all lowercase letter shapes on a 14-segment display, but you can do all uppercase, so I'm assuming they went with that for consistency.
DSEG7 uses some lower case forms (e.g. for "b", "n", "t") to avoid letter shapes which are impossible to represent on a 7-segment display (like "N"), or which would be ambiguous (e.g. "B" / "8").
You still can't represent all lowercase letter shapes on a 14-segment display, but you can do all uppercase, so I'm assuming they went with that for consistency.