Yes, if I had to make something like EB from scratch I probably would prefer something along this line too: it is a bit more straight foreward, saves building slots and is less restrictive in terms of "what-if". But changing the entire EDB, script, descr_start and whatsnot else of EB only to get it in doesn't pay back the effort.

Most of the factions have a rather large AOR for their basic units, in particular the Hellenic and Celtic factions, so playing one of those wouldn't give a dramatic difference. The Romans have their Marians what can be recruited all over the map, what would leave the question to some factions like the Sweboz, Lusotans, Saba and the like.