So the real reason they should delatinize is that Rome wants them too?
Heh. Of course the answer is Rome wants them to because those Orthodox traditions are in themselves good. The more they flourish in the Greek Catholic churches, the more credible union with Rome looks.
The reason we should delatinize is because Latinizations are arbitrary additions that run counter to our way of prayer and worship, much like how egregious random departures from tradition on the Orthodox side (I've seen them) are counter to the way or prayer and worship, or how various "abuses" in the Latin liturgy are spiritually harmful for the Latins.
The "Byzantine" typikon has its own spirituality, logic and reasoning. Oftentimes, perhaps even the majority of times, "Latinization" happened for no good reason beyond "it's the local Latins want us to do so" or (even worse) "it's what we think the Latins want us to do and we'll do it so we fit in". Putting these arbitrary things into our typikon (magnified by the fact that we often don't have the material or often even the spiritual resources to properly pray even a decent slice of the typikon) makes no sense, and destroys the rationale for why we pray what we pray.
(I'm not opposed to change, but there are proper ways changes need to be made, i.e. slowly, with understanding of why we pray what we pray and do what we do, and with consideration and coordination with our eparchal and patriarchal hierarchy and with local sister churches who share our way of prayer. Deviations from the books should be done for carefully chosen spiritual benefit, rather than because we think they're cool, because we think it will make us fit in, or because it fits a pastoral plan we dreamed up any less than a decade ago).
To the OP: I will make an answer, it'll take a while though.