Consider Deuteronomy 28:30, in the Vulgata:
Uxorem accipias, et alius dormiat cum ea. Domum ædifices, et non habites in ea. Plantes vineam, et non vindemies eam.
So uxorem, domum, vineam, and eam are all in accusative. This is, they decline pro/nouns acting as direct objects to a transitive verb. However, because the verb is already declined (and thus indicating the person/subject "acting" the verb), further declining the direct object seems to me redundant.
For instance, if we use the nominative instead, we would get:
Uxor accipias, et alius dormiat cum ea. Domus ædifices, et non habites in ea. Plantes vineus, et non vindemies ea.
Would experienced Latin users (so not me) see an ambiguity in the above phrase? Accipias is clearly second person singular, so it should be clear that "you" are performing the verb, and not a wife. Clearly the house is not building something (what would it be building? as far as I know, to build is not an intransitive verb). Thus, it is "you" who is building houses. And etc.
My question arises because, even as a total beginner in Latin (so I can be wrong), the verb accipias already tells me who is performing the action, so its clear its not the wife. Similarly, it is evident that a house cannot be the subject of the verb to build. Thus, in a sense, I find redundant that I need to learn another grammatical case for pro/nouns. Even if I would be et non vindemies ea I think I would have understand the meaning. This is, the nominative might do a pretty good job replacing the accusative.
So, to rephrase my question, what potential ambiguities is the accusative mode clearing out, so that to make it necessary? I know this mode is inherited from Greek, so maybe is there something peculiar to Greek that required such mode?