Only issue is that the more low-/no-effort MTL 'translations'are used on series with no pushback from the community, the higher the risk of those 'slow, quality TL groups' getting discouraged and stopping doing it altogether due to apparent apathy when it comes to actually-good translation work.
It might be quick and free, but if everyone simply accepts it, then pretty soon it will be the only thing you have--and it will be done by people who care nothing for spell-checking, proofreading, typesetting, or any of the other work that goes into a polished TL release. Shit takes time, and most who are going to the effort, are doing it as a labor of love for the series they like. If there's no appreciation from the community, I would not be surprised if they simply stopped. Some have already, due to repeated MTL sniping.
If that's fine by you, though, then have at.