charleski, more importantly, scholars are able to unambiguously set Cretan scripts and discuss them unambiguously.
If one wants ligatures it's simple enough to set a run of text and turn them on --- no need for unique code points which aren't practical in any case --- there are simply too many possibilities. I had to do quite a bit of fiddling to manage to encode just the options in Zapfino:
http://www.tug.org/TUGboat/Articles/.../tb77adams.pdf
Assigning codepoints for ligatures would be nightmarish and would quickly exhaust them.