Glyphs and Protective Inscriptions

As anyone who's read it knows, the AD&D Dungeon Masters Guide contains not just excellent advice and suggestions to the referee, but also some odd and easily overlooked details. Take, for example, these examples of possible glyphs of warding at the bottom of page 41:

Gygax suggests that referees "design [their] own or use an encyclopedia to find interesting alphabets to use." He also suggests that the referee might look to the example of The World of Greyhawk  for further runes and glyphs. 
On the next page, while discussing the cleric spell aerial servant, Gygax briefly notes that "the spell caster should be required to show you the form of protective inscription he or she has used when the spell is cast." He then provides illustrations for the three forms mentioned by name in the spell's description in the Players Handbook.
In looking at these two sections, I was reminded that, while AD&D has this reputation in some quarters as being very precise and even nitpicky, especially compared with OD&D, there's still a great deal that's left to the individual referee to resolve. In the case of the glyph of warding, for example, its effect is variable to some degree, with just how some of possibilities (i.e. paralysis, blindness, and energy drain) function left unclear. Similarly, there's no clear mechanical difference, if any is intended, between the three illustrated types of protective inscriptions. It's another one of those things the referee is left to decide for himself. 
Frankly, I see this as a strength in AD&D and indeed any roleplaying game. I have little interest in a RPG that leaves no "creative lacunae" where the referee can exercise his own imagination. Moreover, any game that did attempt to cover every base would necessarily be immense in scope, not to mention length. I'd much rather spend my time playing – and making things up – than seeking out every jot and tittle of the rules. I doubt I'm unique in this regard.