Hieroglyphs and the like require, as you note, another whole typing system, which limits their usefulness.
The abbreviations for texting, on the other hand, use readily available means yet manage to be as obscure (apparently a desirable feature). A rather thorough set of abbreviations has been developed over in the sitelen pi toki pona group on facebook; straightforward acronyms of the OMG variety (ajsm 'a jan sewi mi').
The system here is sort of a middle ground: less obscure than either of the other two. The two problems with it are 1. the fact that there are pairs of words that collapse to the same ('sina' and 'sona' cited, but there are several others -- the word space was not optimally used here) and 2. the temptation to actually use some of the resulting forms as words in their own right (teno, leaped to my eye), carrying the cliche way too far. But many expressions do get used a lot and some form of abbreviation is inevitable, especially given twitter and the like. We should, if not systematize usage, at least keep track of what is being used.