This. The potential few extra victims they might profit from by using impeccable language/appearance probably doesn't compare favourably to the cost of extra time/effort dragging along smarter people for a longer time, that are probably just going to bail later on with high certainty at a stage where appearance is no longer the key factor for believability.
Interesting. Makes sense, though many such emails only attempt to bait the recipient into following a link, whereby malware would be installed via drive-by, or otherwise the user would be prompted to enter sensitive info.
In these cases, it seems that crafting a more professional email to cast the net as wide as possible would be prudent.