They do put crons on older toons to make them relevant again. Datacrons. Omicrons are reserved for new characters that bring a profit. Case in point: look up the lvl9 abilities for Pao, Moff Gideon, Eeth Koth in dcron set 17. MG and Eeth's are so stupidly powerful that CG are already investigating 2 turn meter loops the new crons have created.
Think of dcrons as time-limited omicrons. On the other hand, they work in GAC and TW intsead of being locked to one gamemode.
Also, do you really want more omicrons to apply when we get 3-4 conquest characters per year that have triple omicrons + triple omicron legendaries twice a year? I am constantly behind on omicrons. I don't need HK-47 to get a badass omicron so I can not have that one as well because I still need QA's special.